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C++ || Simple Multi Digit, Decimal & Negative Number Infix To Postfix Conversion & Evaluation

February 05, 2021 admin No comments

The following is sample code which demonstrates the implementation of a multi digit, decimal, and negative number infix to postfix converter and evaluator using C++.

The program demonstrated on this page has the ability to convert and evaluate a single digit, multi digit, decimal number, and/or negative number infix equation. So for example, if the the infix equation of (19.87 * -2) was entered into the program, the converted postfix expression of 19.87 -2 * would display to the screen, as well as the final evaluated answer of -39.74.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

How To Convert Infix To Postfix How To Evaluate A Postfix Expression

1. Overview

The program demonstrated on this page is different from a previous implementation of the same type in that this version does not use a Finite State Machine during the conversion process, which simplifies the implemetation!

This program has the following flow of control:

• Get an infix expression from the user • Convert the infix expression to postfix & isolate all of the math operators, multi digit, decimal, negative and single digit numbers that are found in the postfix expression • Evaluate the postfix expression by breaking the infix string into tokens found from the above step • Display the evaluated answer to the screen

The above steps are implemented below.

2. Infix To Posfix Conversion & Evaluation





		
		
			Multi Digit Infix To Postfix Conversion & Evaluation
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 31, 2014
//    Updated: Feb 5, 2021
//    Taken From: http://programmingnotes.org/
//    File: InToPostEval.cpp
//    Description: The following demonstrates the implementation of an infix to
//      postfix converter and evaluator. This program has the ability to
//      convert and evaluate multi digit, decimal, negative and positive values
// ============================================================================
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <stack>
#include <algorithm>
#include <exception>
#include <stdexcept>

// function prototypes
void displayDirections();
std::string convertInfixToPostfix(std::string infix);
bool isMathOperator(char token);
int orderOfOperations(char token);
double evaluatePostfix(const std::string& postfix);
double calculate(char mathOperator, double value1, double value2);
bool isNumeric(char value);
bool isNumeric(std::string value);
std::vector<std::string> split(const std::string& source, const std::string& delimiters = " ");
std::string replaceAll(const std::string& source
    , const std::string& oldValue, const std::string& newValue);

int main() {
    // declare variables
    std::string infix = "";

    // display directions to user
    displayDirections();

    try {
        // get data from user
        std::cout << "\nPlease enter an Infix expression: ";
        std::getline(std::cin, infix);

        // convert infix to postfix
        std::string postfix = convertInfixToPostfix(infix);

        std::cout << "\nThe Infix expression = " << infix;
        std::cout << "\nThe Postfix expression = " << postfix << std::endl;

        // evaluate the postfix string
        double answer = evaluatePostfix(postfix);

        std::cout << "\nFinal answer = " << answer << std::endl;
    } catch (std::exception& e) {
        std::cout << "\nAn error occurred: " + std::string(e.what()) << std::endl;
    }

    std::cin.get();
    return 0;
}// end of main

void displayDirections() {
// this function displays instructions to the screen
    std::cout << "\n==== Infix To Postfix Conversion & Evaluation ====\n"
        << "\nMath Operators:\n"
        << "+ || Addition\n"
        << "- || Subtraction\n"
        << "* || Multiplication\n"
        << "/ || Division\n"
        << "% || Modulus\n"
        << "^ || Power\n"
        << "$ || Square Root\n"
        << "s || Sine\n"
        << "c || Cosine\n"
        << "t || Tangent\n"
        << "- || Negative Number\n"
        << "Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23))\n";
    // ((sin(-4^5)*1.4)/(sqrt(23+2)--2.8))*(cos(1%2)/(7.28*.1987)^(tan(23)))
}// end of displayDirections

std::string convertInfixToPostfix(std::string infix) {
// this function converts an infix expression to postfix
        // declare function variables
    std::string postfix;
    std::stack<char> charStack;

    // remove all whitespace from the string
    infix.erase(std::remove_if(infix.begin(), infix.end(), [](char c) {
        return std::isspace(static_cast<unsigned char>(c));
    }), infix.end());

    // negate equations marked with '--'
    infix = replaceAll(infix, "(--", "(");

    // automatically convert negative numbers to have the ~ symbol.
    // this is done so we can distinguish negative numbers and the subtraction symbol
    for (unsigned x = 0; x < infix.length(); ++x) {
        if (infix[x] != '-') {
            continue;
        }
        if (x == 0 || infix[x - 1] == '(' || isMathOperator(infix[x - 1])) {
            infix[x] = '~';
        }
    }

    // loop thru array until there is no more data
    for (unsigned x = 0; x < infix.length(); ++x) {
        // place numbers (standard, decimal, & negative)
        // numbers onto the 'postfix' string
        if (isNumeric(infix[x])) {
            if (postfix.length() > 0 && !isNumeric(postfix.back())) {
                if (!std::isspace(postfix.back())) {
                    postfix += " ";
                }
            }
            postfix += infix[x];

        } else if (std::isspace(infix[x])) {
            continue;

        } else if (isMathOperator(infix[x])) {
            if (postfix.length() > 0 && !std::isspace(postfix.back())) {
                postfix += " ";
            }
            // use the 'orderOfOperations' function to check equality
            // of the math operator at the top of the stack compared to
            // the current math operator in the infix string
            while ((!charStack.empty()) &&
                (orderOfOperations(charStack.top()) >= orderOfOperations(infix[x]))) {
                // place the math operator from the top of the
                // stack onto the postfix string and continue the
                // process until complete
                if (postfix.length() > 0 && !std::isspace(postfix.back())) {
                    postfix += " ";
                }
                postfix += charStack.top();
                charStack.pop();
            }
            // push the remaining math operator onto the stack
            charStack.push(infix[x]);
        }
        // push outer parentheses onto stack
        else if (infix[x] == '(') {
            charStack.push(infix[x]);

        } else if (infix[x] == ')') {
            // pop the current math operator from the stack
            while ((!charStack.empty()) && (charStack.top() != '(')) {
                if (postfix.length() > 0 && !std::isspace(postfix.back())) {
                    postfix += " ";
                }
                // place the math operator onto the postfix string
                postfix += charStack.top();
                // pop the next operator from the stack and
                // continue the process until complete
                charStack.pop();
            }

            // pop '(' symbol off the stack
            if (!charStack.empty()) {
                charStack.pop();
            } else {
                // no matching '('
                throw std::invalid_argument{ "PARENTHESES MISMATCH" };
            }
        } else {
            throw std::invalid_argument{ "INVALID INPUT" };
        }
    }

    // place any remaining math operators from the stack onto
    // the postfix array
    while (!charStack.empty()) {
        if (charStack.top() == '(' || charStack.top() == ')') {
            throw std::invalid_argument{ "PARENTHESES MISMATCH" };
        }
        if (postfix.length() > 0 && !std::isspace(postfix.back())) {
            postfix += " ";
        }
        postfix += charStack.top();
        charStack.pop();
    }

    // replace all '~' symbols with a minus sign
    postfix = replaceAll(postfix, "~", "-");

    return postfix;
}// end of convertInfixToPostfix

bool isMathOperator(char token) {
// this function checks if operand is a math operator
    switch (std::tolower(token)) {
        case '+': case '-': case '*': case '/':
        case '%': case '^': case '$': case 'c':
        case 's': case 't':
            return true;
            break;
        default:
            return false;
            break;
    }
}// end of isMathOperator

int orderOfOperations(char token) {
// this function returns the priority of each math operator
    int priority = 0;
    switch (std::tolower(token)) {
        case 'c': case 's': case 't':
            priority = 5;
            break;
        case '^': case '$':
            priority = 4;
            break;
        case '*': case '/': case '%':
            priority = 3;
            break;
        case '-':
            priority = 2;
            break;
        case '+':
            priority = 1;
            break;
    }
    return priority;
}// end of orderOfOperations

double evaluatePostfix(const std::string& postfix) {
// this function evaluates a postfix expression
    // declare function variables
    double answer = 0;
    std::stack<double> doubleStack;

    // split string into tokens to isolate multi digit, negative and decimal
    // numbers, aswell as single digit numbers and math operators
    auto tokens = split(postfix);

    // display the found tokens to the screen
    //for (unsigned x = 0; x < tokens.size(); ++x) {
    //    std::cout<< tokens.at(x) << std::endl;
    //}

    std::cout << "\nCalculations:\n";

    // loop thru array until there is no more data
    for (unsigned x = 0; x < tokens.size(); ++x) {
        auto token = tokens[x];

        // push numbers & negative numbers onto the stack
        if (isNumeric(token)) {
            doubleStack.push(std::atof(token.c_str()));
        }
        // if expression is a math operator, pop numbers from stack
        // & send the popped numbers to the 'calculate' function
        else if (isMathOperator(token[0]) && (!doubleStack.empty())) {
            double value1 = 0;
            double value2 = 0;
            char mathOperator = static_cast<unsigned char>(std::tolower(token[0]));

            // if expression is square root, sin, cos,
            // or tan operation only pop stack once
            if (mathOperator == '$' || mathOperator == 's' || mathOperator == 'c' || mathOperator == 't') {
                value2 = 0;
                value1 = doubleStack.top();
                doubleStack.pop();
                answer = calculate(mathOperator, value1, value2);
                doubleStack.push(answer);

            } else if (doubleStack.size() > 1) {
                value2 = doubleStack.top();
                doubleStack.pop();
                value1 = doubleStack.top();
                doubleStack.pop();
                answer = calculate(mathOperator, value1, value2);
                doubleStack.push(answer);
            }
        } else {
            // this should never execute, & if it does, something went really wrong
            throw std::invalid_argument{ "INVALID POSTFIX STRING" };
        }
    }
    // pop the final answer from the stack, and return to main
    if (!doubleStack.empty()) {
        answer = doubleStack.top();
    }
    return answer;
}// end of evaluatePostfix

double calculate(char mathOperator, double value1, double value2) {
// this function carries out the actual math process
    double ans = 0;
    switch (std::tolower(mathOperator)) {
        case '+':
            std::cout << value1 << mathOperator << value2;
            ans = value1 + value2;
            break;
        case '-':
            std::cout << value1 << mathOperator << value2;
            ans = value1 - value2;
            break;
        case '*':
            std::cout << value1 << mathOperator << value2;
            ans = value1 * value2;
            break;
        case '/':
            std::cout << value1 << mathOperator << value2;
            ans = value1 / value2;
            break;
        case '%':
            std::cout << value1 << mathOperator << value2;
            ans = ((int)value1 % (int)value2) + std::modf(value1, &value2);
            break;
        case '^':
            std::cout << value1 << mathOperator << value2;
            ans = std::pow(value1, value2);
            break;
        case '$':
            std::cout << char(251) << value1;
            ans = std::sqrt(value1);
            break;
        case 'c':
            std::cout << "cos(" << value1 << ")";
            ans = std::cos(value1);
            break;
        case 's':
            std::cout << "sin(" << value1 << ")";
            ans = std::sin(value1);
            break;
        case 't':
            std::cout << "tan(" << value1 << ")";
            ans = std::tan(value1);
            break;
        default:
            ans = 0;
            break;
    }
    std::cout << " = " << ans << std::endl;
    return ans;
}// end of calculate

std::vector<std::string> split(const std::string& source, const std::string& delimiters) {
    std::size_t prev = 0;
    std::size_t currentPos = 0;
    std::vector<std::string> results;

    while ((currentPos = source.find_first_of(delimiters, prev)) != std::string::npos) {
        if (currentPos > prev) {
            results.push_back(source.substr(prev, currentPos - prev));
        }
        prev = currentPos + 1;
    }
    if (prev < source.length()) {
        results.push_back(source.substr(prev, std::string::npos));
    }
    return results;
}// end of split

std::string replaceAll(const std::string& source
    , const std::string& oldValue, const std::string& newValue) {
    if (oldValue.empty()) {
        return source;
    }
    std::string newString;
    newString.reserve(source.length());
    std::size_t lastPos = 0;
    std::size_t findPos;
    while (std::string::npos != (findPos = source.find(oldValue, lastPos))) {
        newString.append(source, lastPos, findPos - lastPos);
        newString += newValue;
        lastPos = findPos + oldValue.length();
    }
    newString += source.substr(lastPos);
    return newString;
}// end of replaceAll

bool isNumeric(char value) {
    return std::isdigit(value) || value == '.' || value == '~';
}// end of isNumeric

bool isNumeric(std::string value) {
    for (unsigned index = 0; index < value.length(); ++index) {
        if (index == 0 && value[index] == '-' && value.length() > 1) {
            continue;
        }
        if (!isNumeric(value[index])) {
            return false;
        }
    }
    return true;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 31, 2014
//    Updated: Feb 5, 2021
//    Taken From: http://programmingnotes.org/
//    File: InToPostEval.cpp
//    Description: The following demonstrates the implementation of an infix to
//      postfix converter and evaluator. This program has the ability to
//      convert and evaluate multi digit, decimal, negative and positive values
// ============================================================================
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <stack>
#include <algorithm>
#include <exception>
#include <stdexcept>
 
// function prototypes
void displayDirections();
std::string convertInfixToPostfix(std::string infix);
bool isMathOperator(char token);
int orderOfOperations(char token);
double evaluatePostfix(const std::string& postfix);
double calculate(char mathOperator, double value1, double value2);
bool isNumeric(char value);
bool isNumeric(std::string value);
std::vector<std::string> split(const std::string& source, const std::string& delimiters = " ");
std::string replaceAll(const std::string& source
    , const std::string& oldValue, const std::string& newValue);
 
int main() {
    // declare variables
    std::string infix = "";
 
    // display directions to user
    displayDirections();
 
    try {
        // get data from user
        std::cout << "\nPlease enter an Infix expression: ";
        std::getline(std::cin, infix);
 
        // convert infix to postfix
        std::string postfix = convertInfixToPostfix(infix);
 
        std::cout << "\nThe Infix expression = " << infix;
        std::cout << "\nThe Postfix expression = " << postfix << std::endl;
 
        // evaluate the postfix string
        double answer = evaluatePostfix(postfix);
 
        std::cout << "\nFinal answer = " << answer << std::endl;
    } catch (std::exception& e) {
        std::cout << "\nAn error occurred: " + std::string(e.what()) << std::endl;
    }
 
    std::cin.get();
    return 0;
}// end of main
 
void displayDirections() {
// this function displays instructions to the screen
    std::cout << "\n==== Infix To Postfix Conversion & Evaluation ====\n"
        << "\nMath Operators:\n"
        << "+ || Addition\n"
        << "- || Subtraction\n"
        << "* || Multiplication\n"
        << "/ || Division\n"
        << "% || Modulus\n"
        << "^ || Power\n"
        << "$ || Square Root\n"
        << "s || Sine\n"
        << "c || Cosine\n"
        << "t || Tangent\n"
        << "- || Negative Number\n"
        << "Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23))\n";
    // ((sin(-4^5)*1.4)/(sqrt(23+2)--2.8))*(cos(1%2)/(7.28*.1987)^(tan(23)))
}// end of displayDirections
 
std::string convertInfixToPostfix(std::string infix) {
// this function converts an infix expression to postfix
        // declare function variables
    std::string postfix;
    std::stack<char> charStack;
 
    // remove all whitespace from the string
    infix.erase(std::remove_if(infix.begin(), infix.end(), [](char c) {
        return std::isspace(static_cast<unsigned char>(c));
    }), infix.end());
 
    // negate equations marked with '--'
    infix = replaceAll(infix, "(--", "(");
 
    // automatically convert negative numbers to have the ~ symbol.
    // this is done so we can distinguish negative numbers and the subtraction symbol
    for (unsigned x = 0; x < infix.length(); ++x) {
        if (infix[x] != '-') {
            continue;
        }
        if (x == 0 || infix[x - 1] == '(' || isMathOperator(infix[x - 1])) {
            infix[x] = '~';
        }
    }
 
    // loop thru array until there is no more data
    for (unsigned x = 0; x < infix.length(); ++x) {
        // place numbers (standard, decimal, & negative)
        // numbers onto the 'postfix' string
        if (isNumeric(infix[x])) {
            if (postfix.length() > 0 && !isNumeric(postfix.back())) {
                if (!std::isspace(postfix.back())) {
                    postfix += " ";
                }
            }
            postfix += infix[x];
 
        } else if (std::isspace(infix[x])) {
            continue;
 
        } else if (isMathOperator(infix[x])) {
            if (postfix.length() > 0 && !std::isspace(postfix.back())) {
                postfix += " ";
            }
            // use the 'orderOfOperations' function to check equality
            // of the math operator at the top of the stack compared to
            // the current math operator in the infix string
            while ((!charStack.empty()) &&
                (orderOfOperations(charStack.top()) >= orderOfOperations(infix[x]))) {
                // place the math operator from the top of the
                // stack onto the postfix string and continue the
                // process until complete
                if (postfix.length() > 0 && !std::isspace(postfix.back())) {
                    postfix += " ";
                }
                postfix += charStack.top();
                charStack.pop();
            }
            // push the remaining math operator onto the stack
            charStack.push(infix[x]);
        }
        // push outer parentheses onto stack
        else if (infix[x] == '(') {
            charStack.push(infix[x]);
 
        } else if (infix[x] == ')') {
            // pop the current math operator from the stack
            while ((!charStack.empty()) && (charStack.top() != '(')) {
                if (postfix.length() > 0 && !std::isspace(postfix.back())) {
                    postfix += " ";
                }
                // place the math operator onto the postfix string
                postfix += charStack.top();
                // pop the next operator from the stack and
                // continue the process until complete
                charStack.pop();
            }
 
            // pop '(' symbol off the stack
            if (!charStack.empty()) {
                charStack.pop();
            } else {
                // no matching '('
                throw std::invalid_argument{ "PARENTHESES MISMATCH" };
            }
        } else {
            throw std::invalid_argument{ "INVALID INPUT" };
        }
    }
 
    // place any remaining math operators from the stack onto
    // the postfix array
    while (!charStack.empty()) {
        if (charStack.top() == '(' || charStack.top() == ')') {
            throw std::invalid_argument{ "PARENTHESES MISMATCH" };
        }
        if (postfix.length() > 0 && !std::isspace(postfix.back())) {
            postfix += " ";
        }
        postfix += charStack.top();
        charStack.pop();
    }
 
    // replace all '~' symbols with a minus sign
    postfix = replaceAll(postfix, "~", "-");
 
    return postfix;
}// end of convertInfixToPostfix
 
bool isMathOperator(char token) {
// this function checks if operand is a math operator
    switch (std::tolower(token)) {
        case '+': case '-': case '*': case '/':
        case '%': case '^': case '$': case 'c':
        case 's': case 't':
            return true;
            break;
        default:
            return false;
            break;
    }
}// end of isMathOperator
 
int orderOfOperations(char token) {
// this function returns the priority of each math operator
    int priority = 0;
    switch (std::tolower(token)) {
        case 'c': case 's': case 't':
            priority = 5;
            break;
        case '^': case '$':
            priority = 4;
            break;
        case '*': case '/': case '%':
            priority = 3;
            break;
        case '-':
            priority = 2;
            break;
        case '+':
            priority = 1;
            break;
    }
    return priority;
}// end of orderOfOperations
 
double evaluatePostfix(const std::string& postfix) {
// this function evaluates a postfix expression
    // declare function variables
    double answer = 0;
    std::stack<double> doubleStack;
 
    // split string into tokens to isolate multi digit, negative and decimal
    // numbers, aswell as single digit numbers and math operators
    auto tokens = split(postfix);
 
    // display the found tokens to the screen
    //for (unsigned x = 0; x < tokens.size(); ++x) {
    //    std::cout<< tokens.at(x) << std::endl;
    //}
 
    std::cout << "\nCalculations:\n";
 
    // loop thru array until there is no more data
    for (unsigned x = 0; x < tokens.size(); ++x) {
        auto token = tokens[x];
 
        // push numbers & negative numbers onto the stack
        if (isNumeric(token)) {
            doubleStack.push(std::atof(token.c_str()));
        }
        // if expression is a math operator, pop numbers from stack
        // & send the popped numbers to the 'calculate' function
        else if (isMathOperator(token[0]) && (!doubleStack.empty())) {
            double value1 = 0;
            double value2 = 0;
            char mathOperator = static_cast<unsigned char>(std::tolower(token[0]));
 
            // if expression is square root, sin, cos,
            // or tan operation only pop stack once
            if (mathOperator == '$' || mathOperator == 's' || mathOperator == 'c' || mathOperator == 't') {
                value2 = 0;
                value1 = doubleStack.top();
                doubleStack.pop();
                answer = calculate(mathOperator, value1, value2);
                doubleStack.push(answer);
 
            } else if (doubleStack.size() > 1) {
                value2 = doubleStack.top();
                doubleStack.pop();
                value1 = doubleStack.top();
                doubleStack.pop();
                answer = calculate(mathOperator, value1, value2);
                doubleStack.push(answer);
            }
        } else {
            // this should never execute, & if it does, something went really wrong
            throw std::invalid_argument{ "INVALID POSTFIX STRING" };
        }
    }
    // pop the final answer from the stack, and return to main
    if (!doubleStack.empty()) {
        answer = doubleStack.top();
    }
    return answer;
}// end of evaluatePostfix
 
double calculate(char mathOperator, double value1, double value2) {
// this function carries out the actual math process
    double ans = 0;
    switch (std::tolower(mathOperator)) {
        case '+':
            std::cout << value1 << mathOperator << value2;
            ans = value1 + value2;
            break;
        case '-':
            std::cout << value1 << mathOperator << value2;
            ans = value1 - value2;
            break;
        case '*':
            std::cout << value1 << mathOperator << value2;
            ans = value1 * value2;
            break;
        case '/':
            std::cout << value1 << mathOperator << value2;
            ans = value1 / value2;
            break;
        case '%':
            std::cout << value1 << mathOperator << value2;
            ans = ((int)value1 % (int)value2) + std::modf(value1, &value2);
            break;
        case '^':
            std::cout << value1 << mathOperator << value2;
            ans = std::pow(value1, value2);
            break;
        case '$':
            std::cout << char(251) << value1;
            ans = std::sqrt(value1);
            break;
        case 'c':
            std::cout << "cos(" << value1 << ")";
            ans = std::cos(value1);
            break;
        case 's':
            std::cout << "sin(" << value1 << ")";
            ans = std::sin(value1);
            break;
        case 't':
            std::cout << "tan(" << value1 << ")";
            ans = std::tan(value1);
            break;
        default:
            ans = 0;
            break;
    }
    std::cout << " = " << ans << std::endl;
    return ans;
}// end of calculate
 
std::vector<std::string> split(const std::string& source, const std::string& delimiters) {
    std::size_t prev = 0;
    std::size_t currentPos = 0;
    std::vector<std::string> results;
 
    while ((currentPos = source.find_first_of(delimiters, prev)) != std::string::npos) {
        if (currentPos > prev) {
            results.push_back(source.substr(prev, currentPos - prev));
        }
        prev = currentPos + 1;
    }
    if (prev < source.length()) {
        results.push_back(source.substr(prev, std::string::npos));
    }
    return results;
}// end of split
 
std::string replaceAll(const std::string& source
    , const std::string& oldValue, const std::string& newValue) {
    if (oldValue.empty()) {
        return source;
    }
    std::string newString;
    newString.reserve(source.length());
    std::size_t lastPos = 0;
    std::size_t findPos;
    while (std::string::npos != (findPos = source.find(oldValue, lastPos))) {
        newString.append(source, lastPos, findPos - lastPos);
        newString += newValue;
        lastPos = findPos + oldValue.length();
    }
    newString += source.substr(lastPos);
    return newString;
}// end of replaceAll
 
bool isNumeric(char value) {
    return std::isdigit(value) || value == '.' || value == '~';
}// end of isNumeric
 
bool isNumeric(std::string value) {
    for (unsigned index = 0; index < value.length(); ++index) {
        if (index == 0 && value[index] == '-' && value.length() > 1) {
            continue;
        }
        if (!isNumeric(value[index])) {
            return false;
        }
    }
    return true;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

The following is sample output.

====== RUN 1 ======
==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent - || Negative Number Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: 12/3*9 The Infix expression = 12/3*9 The Postfix expression = 12 3 / 9 * Calculations: 12/3 = 4 4*9 = 36 Final answer = 36 ====== RUN 2 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent - || Negative Number Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: -150.89996 - 87.56643 The Infix expression = -150.89996 - 87.56643 The Postfix expression = -150.89996 87.56643 - Calculations: -150.9-87.5664 = -238.466 Final answer = -238.466 ====== RUN 3 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent - || Negative Number Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) The Infix expression = ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) The Postfix expression = -4 5 ^ s 1.4 * 23 2 + $ -2.8 - / 1 2 % c 7.28 .1987 * 23 t ^ / * Calculations: -4^5 = -1024 sin(-1024) = 0.158533 0.158533*1.4 = 0.221947 23+2 = 25 √25 = 5 5--2.8 = 7.8 0.221947/7.8 = 0.0284547 1%2 = 1 cos(1) = 0.540302 7.28*0.1987 = 1.44654 tan(23) = 1.58815 1.44654^1.58815 = 1.79733 0.540302/1.79733 = 0.300614 0.0284547*0.300614 = 0.00855389 Final answer = 0.00855389 ====== RUN 4 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent - || Negative Number Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: (1987 + 1991) * -1 The Infix expression = (1987 + 1991) * -1 The Postfix expression = 1987 1991 + -1 * Calculations: 1987+1991 = 3978 3978*-1 = -3978 Final answer = -3978 ====== RUN 5 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent - || Negative Number Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: (1+(2*((3+(4*5))*6))) The Infix expression = (1+(2*((3+(4*5))*6))) The Postfix expression = 1 2 3 4 5 * + 6 * * + Calculations: 4*5 = 20 3+20 = 23 23*6 = 138 2*138 = 276 1+276 = 277 Final answer = 277

C++ || Multi Digit, Decimal & Negative Number Infix To Postfix Conversion & Evaluation

January 31, 2014 admin 1 Comment

Click Here For Updated Version Of Program

The following is sample code which demonstrates the implementation of a multi digit, decimal, and negative number infix to postfix converter and evaluator using a Finite State Machine

REQUIRED KNOWLEDGE FOR THIS PROGRAM

How To Convert Infix To Postfix How To Evaluate A Postfix Expression What Is A Finite State Machine?

Using a Finite State Machine, the program demonstrated on this page has the ability to convert and evaluate a single digit, multi digit, decimal number, and/or negative number infix equation. So for example, if the the infix equation of (19.87 * -2) was entered into the program, the converted postfix expression of 19.87 ~2* would display to the screen, as well as the final evaluated answer of -39.74.

NOTE: In this program, negative numbers are represented by the “~” symbol on the postfix string. This is used to differentiate between a negative number and a subtraction symbol.

This program has the following flow of control:

• Get an infix expression from the user • Convert the infix expression to postfix • Use a Finite State Machine to isolate all of the math operators, multi digit, decimal, negative and single digit numbers that are found in the postfix expression • Evaluate the postfix expression using the tokens found from the above step • Display the evaluated answer to the screen

The above steps are implemented below.





		
		
			Multi Digit Infix To Postfix Conversion & Evaluation
			
C++
			
			// ============================================================================
//   Author:  Kenneth Perkins
//   Taken From: http://programmingnotes.org/
//   Date:  Jan 31, 2014
//   File: InToPostEval.cpp
//   Description: The following demonstrates the implementation of an infix to
//     postfix converter and evaluator. Using a Finite State Machine, this
//     program has the ability to convert and evaluate multi digit, decimal,
//     negative and positive values.
// ============================================================================
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <stack>
#include <algorithm>
using namespace std;

/* This holds the transition states for our Finite State Machine
    -- They are placed in numerical order for easy understanding within
        the FSM array, which is located below */

enum FSM_TRANSITIONS
{
    REJECT = 0,
    INTEGER,
    REAL,
    NEGATIVE,
    OPERATOR,
    UNKNOWN,
    SPACE
};

/* This is the Finite State Machine
    -- The zero represents a place holder, so the row in the array
            starts on row 1 instead of 0

                           integer,  real,  negative, operator, unknown, space */
int stateTable[][7] = { {0, INTEGER,  REAL, NEGATIVE, OPERATOR,  UNKNOWN,  SPACE},
/* STATE 1 */   {INTEGER,  INTEGER,  REAL,   REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 2 */   {REAL,       REAL,  REJECT,  REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 3 */   {NEGATIVE, INTEGER,  REAL,   REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 4 */   {OPERATOR,  REJECT, REJECT,  REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 5 */   {UNKNOWN,   REJECT, REJECT,  REJECT,  REJECT,   UNKNOWN, REJECT},
/* STATE 6 */   {SPACE,     REJECT, REJECT,  REJECT,  REJECT,   REJECT,  REJECT} };

// function prototypes
void DisplayDirections();
string ConvertInfixToPostfix(string infix);
bool IsMathOperator(char token);
int OrderOfOperations(char token);
vector<string> Lexer(string postfix);
int Get_FSM_Col(char& currentChar);
double EvaluatePostfix(const vector<string>& postfix);
double Calculate(char token, double op1, double op2);

int main()
{
    // declare variables
    string infix = "";
    string postfix = "";
    double answer = 0;
    vector<string> tokens;

    // display directions to user
    DisplayDirections();

    // get data from user
    cout << "\nPlease enter an Infix expression: ";
    getline(cin, infix);

    postfix = ConvertInfixToPostfix(infix);

    // use the "Lexer" function to isolate multi digit, negative and decimal
    // numbers, aswell as single digit numbers and math operators
    tokens = Lexer(postfix);

    // display the found tokens to the screen
    //for (unsigned x = 0; x < tokens.size(); ++x)
    //{
    //    cout<<tokens.at(x)<<endl;
    //}

    cout << "\nThe Infix expression = " << infix;
    cout << "\nThe Postfix expression = " << postfix << endl;

    answer = EvaluatePostfix(tokens);

    cout << "\nFinal answer = " << answer << endl;

    cin.get();
    return 0;
}// end of main

void DisplayDirections()
{// this function displays instructions to the screen
    cout << "\n==== Infix To Postfix Conversion & Evaluation ====\n"
        << "\nMath Operators:\n"
        << "+ || Addition\n"
        << "- || Subtraction\n"
        << "* || Multiplication\n"
        << "/ || Division\n"
        << "% || Modulus\n"
        << "^ || Power\n"
        << "$ || Square Root\n"
        << "s || Sine\n"
        << "c || Cosine\n"
        << "t || Tangent\n"
        << "- || Negative Number\n"
        << "Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23))\n";
    // ((sin(-4^5)*1.4)/(sqrt(23+2)--2.8))*(cos(1%2)/(7.28*.1987)^(tan(23)))
}// end of DisplayDirections

string ConvertInfixToPostfix(string infix)
{// this function converts an infix expression to postfix
    // declare function variables
    string postfix;
    stack<char> charStack;

    // remove all whitespace from the string
    infix.erase(std::remove_if(infix.begin(), infix.end(), [](char c) {
        return std::isspace(static_cast<unsigned char>(c));
    }), infix.end());

    // automatically convert negative numbers to have the ~ symbol
    for (unsigned x = 0; x < infix.length(); ++x) {
        if (infix[x] != '-') {
            continue;
        } else if (x + 1 < infix.length() && IsMathOperator(infix[x + 1])) {
            continue;
        }
        if (x == 0 || infix[x - 1] == '(' || IsMathOperator(infix[x - 1])) {
            infix[x] = '~';
        }
    }

    // loop thru array until there is no more data
    for (unsigned x = 0; x < infix.length(); ++x)
    {
        // place numbers (standard, decimal, & negative)
        // numbers onto the 'postfix' string
        if ((isdigit(infix[x])) || (infix[x] == '.') || (infix[x] == '~'))
        {
            postfix += infix[x];
        }
        else if (isspace(infix[x]))
        {
            continue;
        }
        else if (IsMathOperator(infix[x]))
        {
            postfix += " ";
            // use the 'OrderOfOperations' function to check equality
            // of the math operator at the top of the stack compared to
            // the current math operator in the infix string
            while ((!charStack.empty()) &&
                (OrderOfOperations(charStack.top()) >= OrderOfOperations(infix[x])))
            {
                // place the math operator from the top of the
                // stack onto the postfix string and continue the
                // process until complete
                postfix += charStack.top();
                charStack.pop();
            }
            // push the remaining math operator onto the stack
            charStack.push(infix[x]);
        }
        // push outer parentheses onto stack
        else if (infix[x] == '(')
        {
            charStack.push(infix[x]);
        }
        else if (infix[x] == ')')
        {
            // pop the current math operator from the stack
            while ((!charStack.empty()) && (charStack.top() != '('))
            {
                // place the math operator onto the postfix string
                postfix += charStack.top();
                // pop the next operator from the stack and
                // continue the process until complete
                charStack.pop();
            }

            if (!charStack.empty()) // pop '(' symbol off the stack
            {
                charStack.pop();
            }
            else // no matching '('
            {
                cout << "\nPARENTHESES MISMATCH #1\n";
                exit(1);
            }
        }
        else
        {
            cout << "\nINVALID INPUT #1\n";
            exit(1);
        }
    }

    // place any remaining math operators from the stack onto
    // the postfix array
    while (!charStack.empty())
    {
        postfix += charStack.top();
        charStack.pop();
    }

    return postfix;
}// end of ConvertInfixToPostfix

bool IsMathOperator(char token)
{// this function checks if operand is a math operator
    switch (tolower(token))
    {
    case '+': case '-': case '*': case '/':
    case '%': case '^': case '$': case 'c':
    case 's': case 't':
        return true;
        break;
    default:
        return false;
        break;
    }
}// end of IsMathOperator

int OrderOfOperations(char token)
{// this function returns the priority of each math operator
    int priority = 0;
    switch (tolower(token))
    {
    case 'c': case 's': case 't':
        priority = 5;
        break;
    case '^': case '$':
        priority = 4;
        break;
    case '*': case '/': case '%':
        priority = 3;
        break;
    case '-':
        priority = 2;
        break;
    case '+':
        priority = 1;
        break;
    }
    return priority;
}// end of OrderOfOperations

vector<string> Lexer(string postfix)
{// this function parses a postfix string using an FSM to generate
 //  each individual token in the expression
    vector<string> tokens;
    char currentChar = ' ';
    int col = REJECT;
    int currentState = REJECT;
    string currentToken = "";

    // use an FSM to parse multidigit and decimal numbers
    // also does error check for invalid input of decimals
    for (unsigned x = 0; x < postfix.length();)
    {
        currentChar = postfix[x];

        // get the column number for the current character
        col = Get_FSM_Col(currentChar);

        // exit if the real number has multiple periods "."
        // in the expression (i.e: 19.3427.23)
        if ((currentState == REAL) && (col == REAL))
        {
            cerr << "\nINVALID INPUT #2\n";
            exit(1);
        }
        /* ========================================================

            THIS IS WHERE WE CHECK THE FINITE STATE MACHINE TABLE
               USING THE "col" VARIABLE FROM ABOVE ^

          ========================================================= */

          // get the current state of our machine
        currentState = stateTable[currentState][col];

        /* ===================================================

          THIS IS WHERE WE CHECK FOR A SUCCESSFUL PARSE
           - If the current state in our machine == REJECT
             (the starting state), then we have successfully parsed
             a token, which is returned to its caller

            - ELSE we continue trying to find a successful token

            =================================================== */
        if (currentState == REJECT)
        {
            if (currentToken != " ") // we dont care about whitespace
            {
                tokens.push_back(currentToken);
            }
            currentToken = "";
        }
        else
        {
            currentToken += currentChar;
            ++x;
        }

    }
    // this ensures the last token gets saved when
    // we reach the end of the postfix string buffer
    if (currentToken != " ") // we dont care about whitespace
    {
        tokens.push_back(currentToken);
    }
    return tokens;
}// end of Lexer

int Get_FSM_Col(char& currentChar)
{// this function determines the state of the type of character being examined
    // check for whitespace
    if (isspace(currentChar))
    {
        return SPACE;
    }

    // check for integer numbers
    else if (isdigit(currentChar))
    {
        return INTEGER;
    }

    // check for real numbers
    else if (currentChar == '.')
    {
        return REAL;
    }

    // check for negative numbers
    else if (currentChar == '~')
    {
        currentChar = '-';
        return NEGATIVE;
    }

    // check for math operators
    else if (IsMathOperator(currentChar))
    {
        return OPERATOR;
    }
    return UNKNOWN;
}// end of Get_FSM_Col

double EvaluatePostfix(const vector<string>& postfix)
{// this function evaluates a postfix expression
    // declare function variables
    double op1 = 0;
    double op2 = 0;
    double answer = 0;
    stack<double> doubleStack;

    cout << "\nCalculations:\n";

    // loop thru array until there is no more data
    for (unsigned x = 0; x < postfix.size(); ++x)
    {
        // push numbers onto the stack
        if ((isdigit(postfix[x][0])) || (postfix[x][0] == '.'))
        {
            doubleStack.push(atof(postfix[x].c_str()));
        }
        // push negative numbers onto the stack
        else if ((postfix[x].length() > 1) && ((postfix[x][0] == '-') &&
            (isdigit(postfix[x][1]) || (postfix[x][1] == '.'))))
        {
            doubleStack.push(atof(postfix[x].c_str()));
        }
        // if expression is a math operator, pop numbers from stack
        // & send the popped numbers to the 'Calculate' function
        else if (IsMathOperator(postfix[x][0]) && (!doubleStack.empty()))
        {
            char token = tolower(postfix[x][0]);

            // if expression is square root, sin, cos,
            // or tan operation only pop stack once
            if (token == '$' || token == 's' || token == 'c' || token == 't')
            {
                op2 = 0;
                op1 = doubleStack.top();
                doubleStack.pop();
                answer = Calculate(token, op1, op2);
                doubleStack.push(answer);
            }
            else if (doubleStack.size() > 1)
            {
                op2 = doubleStack.top();
                doubleStack.pop();
                op1 = doubleStack.top();
                doubleStack.pop();
                answer = Calculate(token, op1, op2);
                doubleStack.push(answer);
            }
        }
        else // this should never execute, & if it does, something went really wrong
        {
            cout << "\nINVALID INPUT #3\n";
            exit(1);
        }
    }
    // pop the final answer from the stack, and return to main
    if (!doubleStack.empty())
    {
        answer = doubleStack.top();
    }
    return answer;
}// end of EvaluatePostfix

double Calculate(char token, double op1, double op2)
{// this function carries out the actual math process
    double ans = 0;
    switch (tolower(token))
    {
    case '+':
        cout << op1 << token << op2 << " = ";
        ans = op1 + op2;
        break;
    case '-':
        cout << op1 << token << op2 << " = ";
        ans = op1 - op2;
        break;
    case '*':
        cout << op1 << token << op2 << " = ";
        ans = op1 * op2;
        break;
    case '/':
        cout << op1 << token << op2 << " = ";
        ans = op1 / op2;
        break;
    case '%':
        cout << op1 << token << op2 << " = ";
        ans = ((int)op1 % (int)op2) + modf(op1, &op2);
        break;
    case '^':
        cout << op1 << token << op2 << " = ";
        ans = pow(op1, op2);
        break;
    case '$':
        cout << char(251) << op1 << " = ";
        ans = sqrt(op1);
        break;
    case 'c':
        cout << "cos(" << op1 << ") = ";
        ans = cos(op1);
        break;
    case 's':
        cout << "sin(" << op1 << ") = ";
        ans = sin(op1);
        break;
    case 't':
        cout << "tan(" << op1 << ") = ";
        ans = tan(op1);
        break;
    default:
        ans = 0;
        break;
    }
    cout << ans << endl;
    return ans;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author:  Kenneth Perkins
//   Taken From: http://programmingnotes.org/
//   Date:  Jan 31, 2014
//   File: InToPostEval.cpp
//   Description: The following demonstrates the implementation of an infix to
//     postfix converter and evaluator. Using a Finite State Machine, this
//     program has the ability to convert and evaluate multi digit, decimal,
//     negative and positive values.
// ============================================================================
#include <iostream>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <string>
#include <vector>
#include <stack>
#include <algorithm>
using namespace std;
 
/* This holds the transition states for our Finite State Machine
    -- They are placed in numerical order for easy understanding within
        the FSM array, which is located below */
 
enum FSM_TRANSITIONS
{
    REJECT = 0,
    INTEGER,
    REAL,
    NEGATIVE,
    OPERATOR,
    UNKNOWN,
    SPACE
};
 
/* This is the Finite State Machine
    -- The zero represents a place holder, so the row in the array
            starts on row 1 instead of 0
 
                           integer,  real,  negative, operator, unknown, space */
int stateTable[][7] = { {0, INTEGER,  REAL, NEGATIVE, OPERATOR,  UNKNOWN,  SPACE},
/* STATE 1 */   {INTEGER,  INTEGER,  REAL,   REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 2 */   {REAL,       REAL,  REJECT,  REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 3 */   {NEGATIVE, INTEGER,  REAL,   REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 4 */   {OPERATOR,  REJECT, REJECT,  REJECT,  REJECT,   REJECT,  REJECT},
/* STATE 5 */   {UNKNOWN,   REJECT, REJECT,  REJECT,  REJECT,   UNKNOWN, REJECT},
/* STATE 6 */   {SPACE,     REJECT, REJECT,  REJECT,  REJECT,   REJECT,  REJECT} };
 
// function prototypes
void DisplayDirections();
string ConvertInfixToPostfix(string infix);
bool IsMathOperator(char token);
int OrderOfOperations(char token);
vector<string> Lexer(string postfix);
int Get_FSM_Col(char& currentChar);
double EvaluatePostfix(const vector<string>& postfix);
double Calculate(char token, double op1, double op2);
 
int main()
{
    // declare variables
    string infix = "";
    string postfix = "";
    double answer = 0;
    vector<string> tokens;
 
    // display directions to user
    DisplayDirections();
 
    // get data from user
    cout << "\nPlease enter an Infix expression: ";
    getline(cin, infix);
 
    postfix = ConvertInfixToPostfix(infix);
 
    // use the "Lexer" function to isolate multi digit, negative and decimal
    // numbers, aswell as single digit numbers and math operators
    tokens = Lexer(postfix);
 
    // display the found tokens to the screen
    //for (unsigned x = 0; x < tokens.size(); ++x)
    //{
    //    cout<<tokens.at(x)<<endl;
    //}
 
    cout << "\nThe Infix expression = " << infix;
    cout << "\nThe Postfix expression = " << postfix << endl;
 
    answer = EvaluatePostfix(tokens);
 
    cout << "\nFinal answer = " << answer << endl;
 
    cin.get();
    return 0;
}// end of main
 
void DisplayDirections()
{// this function displays instructions to the screen
    cout << "\n==== Infix To Postfix Conversion & Evaluation ====\n"
        << "\nMath Operators:\n"
        << "+ || Addition\n"
        << "- || Subtraction\n"
        << "* || Multiplication\n"
        << "/ || Division\n"
        << "% || Modulus\n"
        << "^ || Power\n"
        << "$ || Square Root\n"
        << "s || Sine\n"
        << "c || Cosine\n"
        << "t || Tangent\n"
        << "- || Negative Number\n"
        << "Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23))\n";
    // ((sin(-4^5)*1.4)/(sqrt(23+2)--2.8))*(cos(1%2)/(7.28*.1987)^(tan(23)))
}// end of DisplayDirections
 
string ConvertInfixToPostfix(string infix)
{// this function converts an infix expression to postfix
    // declare function variables
    string postfix;
    stack<char> charStack;
 
    // remove all whitespace from the string
    infix.erase(std::remove_if(infix.begin(), infix.end(), [](char c) {
        return std::isspace(static_cast<unsigned char>(c));
    }), infix.end());
 
    // automatically convert negative numbers to have the ~ symbol
    for (unsigned x = 0; x < infix.length(); ++x) {
        if (infix[x] != '-') {
            continue;
        } else if (x + 1 < infix.length() && IsMathOperator(infix[x + 1])) {
            continue;
        }
        if (x == 0 || infix[x - 1] == '(' || IsMathOperator(infix[x - 1])) {
            infix[x] = '~';
        }
    }
 
    // loop thru array until there is no more data
    for (unsigned x = 0; x < infix.length(); ++x)
    {
        // place numbers (standard, decimal, & negative)
        // numbers onto the 'postfix' string
        if ((isdigit(infix[x])) || (infix[x] == '.') || (infix[x] == '~'))
        {
            postfix += infix[x];
        }
        else if (isspace(infix[x]))
        {
            continue;
        }
        else if (IsMathOperator(infix[x]))
        {
            postfix += " ";
            // use the 'OrderOfOperations' function to check equality
            // of the math operator at the top of the stack compared to
            // the current math operator in the infix string
            while ((!charStack.empty()) &&
                (OrderOfOperations(charStack.top()) >= OrderOfOperations(infix[x])))
            {
                // place the math operator from the top of the
                // stack onto the postfix string and continue the
                // process until complete
                postfix += charStack.top();
                charStack.pop();
            }
            // push the remaining math operator onto the stack
            charStack.push(infix[x]);
        }
        // push outer parentheses onto stack
        else if (infix[x] == '(')
        {
            charStack.push(infix[x]);
        }
        else if (infix[x] == ')')
        {
            // pop the current math operator from the stack
            while ((!charStack.empty()) && (charStack.top() != '('))
            {
                // place the math operator onto the postfix string
                postfix += charStack.top();
                // pop the next operator from the stack and
                // continue the process until complete
                charStack.pop();
            }
 
            if (!charStack.empty()) // pop '(' symbol off the stack
            {
                charStack.pop();
            }
            else // no matching '('
            {
                cout << "\nPARENTHESES MISMATCH #1\n";
                exit(1);
            }
        }
        else
        {
            cout << "\nINVALID INPUT #1\n";
            exit(1);
        }
    }
 
    // place any remaining math operators from the stack onto
    // the postfix array
    while (!charStack.empty())
    {
        postfix += charStack.top();
        charStack.pop();
    }
 
    return postfix;
}// end of ConvertInfixToPostfix
 
bool IsMathOperator(char token)
{// this function checks if operand is a math operator
    switch (tolower(token))
    {
    case '+': case '-': case '*': case '/':
    case '%': case '^': case '$': case 'c':
    case 's': case 't':
        return true;
        break;
    default:
        return false;
        break;
    }
}// end of IsMathOperator
 
int OrderOfOperations(char token)
{// this function returns the priority of each math operator
    int priority = 0;
    switch (tolower(token))
    {
    case 'c': case 's': case 't':
        priority = 5;
        break;
    case '^': case '$':
        priority = 4;
        break;
    case '*': case '/': case '%':
        priority = 3;
        break;
    case '-':
        priority = 2;
        break;
    case '+':
        priority = 1;
        break;
    }
    return priority;
}// end of OrderOfOperations
 
vector<string> Lexer(string postfix)
{// this function parses a postfix string using an FSM to generate
 //  each individual token in the expression
    vector<string> tokens;
    char currentChar = ' ';
    int col = REJECT;
    int currentState = REJECT;
    string currentToken = "";
 
    // use an FSM to parse multidigit and decimal numbers
    // also does error check for invalid input of decimals
    for (unsigned x = 0; x < postfix.length();)
    {
        currentChar = postfix[x];
 
        // get the column number for the current character
        col = Get_FSM_Col(currentChar);
 
        // exit if the real number has multiple periods "."
        // in the expression (i.e: 19.3427.23)
        if ((currentState == REAL) && (col == REAL))
        {
            cerr << "\nINVALID INPUT #2\n";
            exit(1);
        }
        /* ========================================================
 
            THIS IS WHERE WE CHECK THE FINITE STATE MACHINE TABLE
               USING THE "col" VARIABLE FROM ABOVE ^
 
          ========================================================= */
 
          // get the current state of our machine
        currentState = stateTable[currentState][col];
 
        /* ===================================================
 
          THIS IS WHERE WE CHECK FOR A SUCCESSFUL PARSE
           - If the current state in our machine == REJECT
             (the starting state), then we have successfully parsed
             a token, which is returned to its caller
 
            - ELSE we continue trying to find a successful token
 
            =================================================== */
        if (currentState == REJECT)
        {
            if (currentToken != " ") // we dont care about whitespace
            {
                tokens.push_back(currentToken);
            }
            currentToken = "";
        }
        else
        {
            currentToken += currentChar;
            ++x;
        }
 
    }
    // this ensures the last token gets saved when
    // we reach the end of the postfix string buffer
    if (currentToken != " ") // we dont care about whitespace
    {
        tokens.push_back(currentToken);
    }
    return tokens;
}// end of Lexer
 
int Get_FSM_Col(char& currentChar)
{// this function determines the state of the type of character being examined
    // check for whitespace
    if (isspace(currentChar))
    {
        return SPACE;
    }
 
    // check for integer numbers
    else if (isdigit(currentChar))
    {
        return INTEGER;
    }
 
    // check for real numbers
    else if (currentChar == '.')
    {
        return REAL;
    }
 
    // check for negative numbers
    else if (currentChar == '~')
    {
        currentChar = '-';
        return NEGATIVE;
    }
 
    // check for math operators
    else if (IsMathOperator(currentChar))
    {
        return OPERATOR;
    }
    return UNKNOWN;
}// end of Get_FSM_Col
 
double EvaluatePostfix(const vector<string>& postfix)
{// this function evaluates a postfix expression
    // declare function variables
    double op1 = 0;
    double op2 = 0;
    double answer = 0;
    stack<double> doubleStack;
 
    cout << "\nCalculations:\n";
 
    // loop thru array until there is no more data
    for (unsigned x = 0; x < postfix.size(); ++x)
    {
        // push numbers onto the stack
        if ((isdigit(postfix[x][0])) || (postfix[x][0] == '.'))
        {
            doubleStack.push(atof(postfix[x].c_str()));
        }
        // push negative numbers onto the stack
        else if ((postfix[x].length() > 1) && ((postfix[x][0] == '-') &&
            (isdigit(postfix[x][1]) || (postfix[x][1] == '.'))))
        {
            doubleStack.push(atof(postfix[x].c_str()));
        }
        // if expression is a math operator, pop numbers from stack
        // & send the popped numbers to the 'Calculate' function
        else if (IsMathOperator(postfix[x][0]) && (!doubleStack.empty()))
        {
            char token = tolower(postfix[x][0]);
 
            // if expression is square root, sin, cos,
            // or tan operation only pop stack once
            if (token == '$' || token == 's' || token == 'c' || token == 't')
            {
                op2 = 0;
                op1 = doubleStack.top();
                doubleStack.pop();
                answer = Calculate(token, op1, op2);
                doubleStack.push(answer);
            }
            else if (doubleStack.size() > 1)
            {
                op2 = doubleStack.top();
                doubleStack.pop();
                op1 = doubleStack.top();
                doubleStack.pop();
                answer = Calculate(token, op1, op2);
                doubleStack.push(answer);
            }
        }
        else // this should never execute, & if it does, something went really wrong
        {
            cout << "\nINVALID INPUT #3\n";
            exit(1);
        }
    }
    // pop the final answer from the stack, and return to main
    if (!doubleStack.empty())
    {
        answer = doubleStack.top();
    }
    return answer;
}// end of EvaluatePostfix
 
double Calculate(char token, double op1, double op2)
{// this function carries out the actual math process
    double ans = 0;
    switch (tolower(token))
    {
    case '+':
        cout << op1 << token << op2 << " = ";
        ans = op1 + op2;
        break;
    case '-':
        cout << op1 << token << op2 << " = ";
        ans = op1 - op2;
        break;
    case '*':
        cout << op1 << token << op2 << " = ";
        ans = op1 * op2;
        break;
    case '/':
        cout << op1 << token << op2 << " = ";
        ans = op1 / op2;
        break;
    case '%':
        cout << op1 << token << op2 << " = ";
        ans = ((int)op1 % (int)op2) + modf(op1, &op2);
        break;
    case '^':
        cout << op1 << token << op2 << " = ";
        ans = pow(op1, op2);
        break;
    case '$':
        cout << char(251) << op1 << " = ";
        ans = sqrt(op1);
        break;
    case 'c':
        cout << "cos(" << op1 << ") = ";
        ans = cos(op1);
        break;
    case 's':
        cout << "sin(" << op1 << ") = ";
        ans = sin(op1);
        break;
    case 't':
        cout << "tan(" << op1 << ") = ";
        ans = tan(op1);
        break;
    default:
        ans = 0;
        break;
    }
    cout << ans << endl;
    return ans;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

The following is sample output.

====== RUN 1 ====== ==== Infix To Postfix Conversion & Evaluation ====
Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent ~ || Negative Number Sample Infix Equation: ((s(~4^5)*1.4)/($(23+2)-~2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: 12/3*9 The Infix expression = 12/3*9 The Postfix expression = 12 3 /9* Calculations: 12/3 = 4 4*9 = 36 Final answer = 36 ====== RUN 2 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent ~ || Negative Number Sample Infix Equation: ((s(~4^5)*1.4)/($(23+2)-~2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: -150.89996 - 87.56643 The Infix expression = -150.89996 - 87.56643 The Postfix expression = ~150.89996 87.56643- Calculations: -150.9-87.5664 = -238.466 Final answer = -238.466 ====== RUN 3 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent ~ || Negative Number Sample Infix Equation: ((s(~4^5)*1.4)/($(23+2)-~2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: ((s(~4^5)*1.4)/($(23+2)-~2.8))*(c(1%2)/(7.28*.1987)^(t23)) The Infix expression = ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) The Postfix expression = ~4 5^ s1.4* 23 2+ $~2.8-/ 1 2% c7.28 .1987* 23t^/* Calculations: -4^5 = -1024 sin(-1024) = 0.158533 0.158533*1.4 = 0.221947 23+2 = 25 √25 = 5 5--2.8 = 7.8 0.221947/7.8 = 0.0284547 1%2 = 1 cos(1) = 0.540302 7.28*0.1987 = 1.44654 tan(23) = 1.58815 1.44654^1.58815 = 1.79733 0.540302/1.79733 = 0.300614 0.0284547*0.300614 = 0.00855389 Final answer = 0.00855389 ====== RUN 4 ====== ==== Infix To Postfix Conversion & Evaluation ==== Math Operators: + || Addition - || Subtraction * || Multiplication / || Division % || Modulus ^ || Power $ || Square Root s || Sine c || Cosine t || Tangent - || Negative Number Sample Infix Equation: ((s(-4^5)*1.4)/($(23+2)--2.8))*(c(1%2)/(7.28*.1987)^(t23)) Please enter an Infix expression: (1987 + 1991) * -1 The Infix expression = (1987 + 1991) * -1 The Postfix expression = 1987 1991+ ~1* Calculations: 1987+1991 = 3978 3978*-1 = -3978 Final answer = -3978

Python || Find The Average Using A List – Omit Highest And Lowest Scores

January 29, 2014 admin No comments

This page will consist of a program which calculates the average of a specific amount of numbers using a list.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Lists For Loops Arithmetic Operators Basic Math - How To Find The Average

The following program is fairly simple, and was used to introduce the list concept. This program prompts the user to enter the total amount of numbers they wish to find the average for, then displays the answer to the screen. Using a sort, this program also has the ability to find the average of a list of numbers, omitting the highest and lowest valued items.





		
		
			Find The Average Using A List
			
Python
			
			# =============================================================================
#   Author:  K Perkins
#   Taken From: http://programmingnotes.org/
#   Date:  Jan 29, 2014
#   File: Average.py
#   Description: The following demonstrates finding the average of numbers
#     contained in a list.
# =============================================================================
# calculate the average of numbers in a list
def Average(arry, size):
    total = 0

    # traverse the list adding all the items together
    for x in range(size):
        total += arry[x]

    # return the average
    return total / size
## end of Average

def main():
    # declare variables
    arry = [] # initialize the list
    numElems = 0

    # ask user how many items they want to place in list
    numElems = int(input("How many items do you want to place into the list?: "))

    # print a newline
    print("")

    # user enters data into list using a for loop
    for x in range(0, numElems):
        arry.append(int(input("Enter item #%d: " % (x+1))))

    # display data
    print("nThe current items inside the list are: ")
    for x in range(0, numElems):
        print("Item #%d: %d" % ((x+1), arry[x]))

    # display the average using a function
    print("nThe average of the %d numbers is %.2f" %
        (numElems, Average(arry, len(arry))))

    # sort the numbers in the list from lowest to highest
    arry.sort()

    # erase the highest/lowest numbers
    arry.pop(len(arry)-1)
    arry.pop(0)

    # display the average using a function
    print("nThe average adjusted score omitting the highest and "
        "lowest result is %.2f" % (Average(arry, len(arry))))
## end of main

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#   Author:  K Perkins
#   Taken From: http://programmingnotes.org/
#   Date:  Jan 29, 2014
#   File: Average.py
#   Description: The following demonstrates finding the average of numbers
#     contained in a list.
# =============================================================================
# calculate the average of numbers in a list
def Average(arry, size):
    total = 0
 
    # traverse the list adding all the items together
    for x in range(size):
        total += arry[x]
 
    # return the average
    return total / size
## end of Average
 
def main():
    # declare variables
    arry = [] # initialize the list
    numElems = 0
 
    # ask user how many items they want to place in list
    numElems = int(input("How many items do you want to place into the list?: "))
 
    # print a newline
    print("")
 
    # user enters data into list using a for loop
    for x in range(0, numElems):
        arry.append(int(input("Enter item #%d: " % (x+1))))
 
    # display data
    print("nThe current items inside the list are: ")
    for x in range(0, numElems):
        print("Item #%d: %d" % ((x+1), arry[x]))
 
    # display the average using a function
    print("nThe average of the %d numbers is %.2f" %
        (numElems, Average(arry, len(arry))))
 
    # sort the numbers in the list from lowest to highest
    arry.sort()
 
    # erase the highest/lowest numbers
    arry.pop(len(arry)-1)
    arry.pop(0)
 
    # display the average using a function
    print("nThe average adjusted score omitting the highest and "
        "lowest result is %.2f" % (Average(arry, len(arry))))
## end of main
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

The following is sample output.

How many items do you want to place into the list?: 5
Enter item #1: 7 Enter item #2: 7 Enter item #3: 4 Enter item #4: 8 Enter item #5: 7 The current items inside the list are: Item #1: 7 Item #2: 7 Item #3: 4 Item #4: 8 Item #5: 7 The average of the 5 numbers is 6.60
The average adjusted score omitting the highest and lowest result is 7.00

C++ || Custom Template Hash Map With Iterator Using Separate Chaining

June 11, 2013 admin No comments

Before we get into the code, what is a Hash Map? Simply put, a Hash Map is an extension of a Hash Table; which is a data structure used to map unique “keys” to specific “values.” The Hash Map demonstrated on this page is different from the previous Hash Table implementation in that key/value pairs do not need to be the same datatype, they can be completely different. So for example, if you wish to map a string “key” to an integer “value“, utilizing a Hash Map is ideal.

In its most simplest form, a Hash Map can be thought of as an associative array, or a “dictionary.” Hash Map’s are composed of a collection of key/value pairs, such that each possible key appears atleast once in the collection for a given value. While a standard array requires that indice subscripts be integers, a hash map can use a string, an integer, or even a floating point value as the index. That index is called the “key,” and the contents within the array at that specific index location is called the “value.” A hash map uses a hash function to generate an index into the table, creating buckets or slots, from which the correct value can be found.

To illustrate, suppose that you’re working with some data that has values associated with strings — for instance, you might have student names and you wish to assign them grades. How would you store this data? Depending on your skill level, you might use multiple arrays during the implementation. For example, in terms of a one dimensional array, if we wanted to access the data for a student located at index #25, we could access it by doing:

studentNames[25]; // do something with the data studentGrades[25];

Here, we dont have to search through each element in the array to find what we need, we just access it at index #25. The question is, how do we know that index #25 holds the data that we are looking for? If we have a large set of data, not only will keeping track of multiple arrays become tiresome, but doing a sequential search over each item within the separate arrays can become very inefficient. That is where hashing comes in handy. Using a Hash Map, we can use the students name as the “key,” and the students grade as the data “value.” Given this “key” (the students name), we can apply a hash function to map a unique index or bucket within the hash table to find the data “value” (the students grade) that we wish to access.

So in essence, a Hash Map is an extension of a hash table, which is a data structure that stores key/value pairs. Hash tables are typically used because they are ideal for doing a quick search of items.

Though hashing is ideal, it isnt perfect. It is possible for multiple “keys” to be hashed into the same location. Hash “collisions” are practically unavoidable when hashing large data sets. The code demonstrated on this page handles collisions via separate chaining, utilizing an array of linked list head nodes to store multiple keys within one bucket – should any collisions occur.

A special feature of this current hash map class is that its implemented as a multimap, meaning that more than one “value” can be associated with a given “key.” For example, in a student enrollment system where students may be enrolled in multiple classes simultaneously, there might be an association for each enrollment where the “key” is the student ID, and the “value” is the course ID. In this example, if a given student is enrolled in three courses, there will be three associated “values” (course ID’s) for one “key” (student ID) in the Hash Map.

An iterator was also implemented, making data access that much more simple within the hash map class. Click here for an overview demonstrating how custom iterators can be built.

=== CUSTOM TEMPLATE HASH MAP WITH ITERATOR ===





		
		
			#include 'HashMap.h' - Hash Map With Iterator
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   June 11, 2013
//    Taken From: http://programmingnotes.org/
//    File:  HashMap.h
//    Description: This is a class which implements various functions
//          demonstrating the use of a Hash Map.
// ============================================================================
#ifndef TEMPLATE_HASH_MAP
#define TEMPLATE_HASH_MAP
#include <iostream>
#include <string>
#include <sstream>
#include <cstdlib>

// if user doesnt define, this is the
// default hash map size
const int HASH_SIZE = 350;

template <class Key, class Value>
class HashMap
{
public:
    HashMap(int hashSze = HASH_SIZE);
        /*   Function: Constructor initializes hash map
            Precondition: None
            Postcondition: Defines private variables */
    bool IsEmpty(int keyIndex);
        /*   Function: Determines whether hash map is empty at the given hash
                            map key index
            Precondition: Hash map has been created
            Postcondition: The function = true if the hash map is empty and the
                             function = false if hash map is not empty */
    bool  IsFull();
        /*   Function: Determines whether hash map is full
            Precondition: Hash map has been created
            Postcondition: The function = true if the hash map is full and the
                             function = false if hash map is not full */
    int Hash(Key m_key);
        /*   Function: Computes and returns a hash map key index for a given item
                        The returned key index is the given cell where the item resides
            Precondition:  Hash map has been created and is not full
            Postcondition: The hash key is returned */
    void Insert(Key m_key, Value m_value);
        /*   Function: Adds new item to the back of the list at a given key in the hash map
                         A unique hash key is automatically generated for each new item
            Precondition:  Hash map has been created and is not full
            Postcondition: Item is in the hash map */
    bool Remove(Key m_key, Value deleteItem);
        /*   Function: Removes the first instance from the map whose value is "deleteItem"
            Precondition:  Hash map has been created and is not empty
            Postcondition: The function = true if deleteItem is found and the
                             function = false if deleteItem is not found */
    void Sort(int keyIndex);
        /*   Function: Sort the items in the map at the given hashmap key index
            Precondition: Hash map has been initialized
            Postcondition: The hash map is sorted */
    int TableSize();
        /*   Function: Return the size of the hash map
            Precondition: Hash map has been initialized
            Postcondition: The size of the hash map is returned */
    int TotalElems();
        /*   Function: Return the total number of elements contained in the hash map
            Precondition: Hash map has been initialized
            Postcondition: The size of the hash map is returned */
    int BucketSize(int keyIndex);
        /*   Function: Return the number of items contained in the hash map
                        cell at the given hashmap key index
            Precondition: Hash map has been initialized
            Postcondition: The size of the given key cell is returned */
    int Count(Key m_key, Value searchItem);
        /*   Function: Return the number of times searchItem appears in the map
                        at the given key
            Precondition: Hash map has been initialized
            Postcondition: The number of times searchItem appears in the map is returned */
    int ContainsKey(Key m_key);
        /*   Function: Return the number of times the given key appears in the hashmap
            Precondition: Hash map has been initialized
            Postcondition: The number of times the given key appears in the map is returned */
    void MakeEmpty();
        /*   Function: Initializes hash map to an empty state
            Precondition: Hash map has been created
            Postcondition: Hash map no longer exists */
    ~HashMap();
        /*   Function: Removes the hash map
            Precondition: Hash map has been declared
            Postcondition: Hash map no longer exists */

    //  -- ITERATOR CLASS --
    class Iterator;
        /*   Function: Class declaration to the iterator
            Precondition: Hash map has been declared
            Postcondition: Hash Iterator has been declared */

    Iterator begin(int keyIndex){return(!IsEmpty(keyIndex)) ? head[keyIndex]:NULL;}
        /*   Function: Returns the beginning of the current hashmap key index
            Precondition: Hash map has been declared
            Postcondition: Hash cell has been returned to the Iterator */

    Iterator end(int keyIndex=0){return NULL;}
        /*   Function: Returns the end of the current hashmap key index
            Precondition: Hash map has been declared
            Postcondition: Hash cell has been returned to the Iterator */

private:
    struct KeyValue  // struct to hold key/value pairs
    {
        Key key;
        Value value;
    };
    struct node
    {
        KeyValue currentItem;
        node* next;
    };
    node** head; // array of linked list declaration - front of each hash map cell
    int hashSize; // the size of the hash map (how many cells it has)
    int totElems; // holds the total number of elements in the entire table
    int* bucketSize; // holds the total number of elems in each specific hash map cell
};

//=========================  Implementation  ================================//

template <class Key, class Value>
HashMap<Key, Value>::HashMap(int hashSze)
{
    hashSize = hashSze;
    head = new node*[hashSize];
    bucketSize = new int[hashSize];
    for(int x=0; x < hashSize; ++x)
    {
        head[x] = NULL;
        bucketSize[x] = 0;
    }
    totElems = 0;
}/* End of HashMap */

template <class Key, class Value>
bool HashMap<Key, Value>::IsEmpty(int keyIndex)
{
    if(keyIndex >=0 && keyIndex < hashSize)
    {
        return head[keyIndex] == NULL;
    }
    return true;
}/* End of IsEmpty */

template <class Key, class Value>
bool HashMap<Key, Value>::IsFull()
{
    try
    {
        node* location = new node;
        delete location;
        return false;
    }
    catch(std::bad_alloc&)
    {
        return true;
    }
}/* End of IsFull */

template <class Key, class Value>
int HashMap<Key, Value>::Hash(Key m_key)
{
    long h = 19937;
    std::stringstream convert;

    // convert the parameter to a string using "stringstream" which is done
    // so we can hash multiple datatypes using only one function
    convert << m_key;
    std::string temp = convert.str();

    for(unsigned x=0; x < temp.length(); ++x)
    {
        h = (h << 6) ^ (h >> 26) ^ temp[x];
    }
    return abs(h % hashSize);
} /* End of Hash */

template <class Key, class Value>
void HashMap<Key, Value>::Insert(Key m_key, Value m_value)
{
    if(IsFull())
    {
        //std::cout<<"\nINSERT ERROR - HASH MAP FULL\n";
    }
    else
    {
        int keyIndex = Hash(m_key);
        node* newNode = new node;   // add new node
        newNode-> currentItem.key = m_key;
        newNode-> currentItem.value = m_value;
        newNode-> next = NULL;

        if(IsEmpty(keyIndex))
        {
            head[keyIndex] = newNode;
        }
        else
        {
            node* temp = head[keyIndex];
            while(temp-> next != NULL)
            {
                temp = temp-> next;
            }
            temp-> next = newNode;
        }
        ++bucketSize[keyIndex];
        ++totElems;
    }
}/* End of Insert */

template <class Key, class Value>
bool HashMap<Key, Value>::Remove(Key m_key, Value deleteItem)
{
    bool isFound = false;
    node* temp;
    int keyIndex = Hash(m_key);

    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nREMOVE ERROR - HASH MAP EMPTY\n";
    }
    else if(head[keyIndex]->currentItem.key == m_key
            && head[keyIndex]->currentItem.value == deleteItem)
    {
        temp = head[keyIndex];
        head[keyIndex] = head[keyIndex]-> next;
        delete temp;
        --totElems;
        --bucketSize[keyIndex];
        isFound = true;
    }
    else
    {
        for(temp = head[keyIndex];temp->next!=NULL;temp=temp->next)
        {
            if(temp->next->currentItem.key == m_key
                && temp->next->currentItem.value == deleteItem)
            {
                node* deleteNode = temp->next;
                temp-> next = temp-> next-> next;
                delete deleteNode;
                isFound = true;
                --totElems;
                --bucketSize[keyIndex];
                break;
            }
        }
    }
    return isFound;
}/* End of Remove */

template <class Key, class Value>
void HashMap<Key, Value>::Sort(int keyIndex)
{
    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nSORT ERROR - HASH MAP EMPTY\n";
    }
    else
    {
        int listSize = BucketSize(keyIndex);
        bool sorted = false;

        do{
            sorted = true;
            int x = 0;
            for(node* temp = head[keyIndex];
                temp->next!=NULL && x < listSize-1;
                temp=temp->next,++x)
            {
                if(temp-> currentItem.value > temp->next->currentItem.value)
                {
                    std::swap(temp-> currentItem,temp->next->currentItem);
                    sorted = false;
                }
            }
            --listSize;
        }while(!sorted);
    }
}/* End of Sort */

template <class Key, class Value>
int HashMap<Key, Value>::TableSize()
{
    return hashSize;
}/* End of TableSize */

template <class Key, class Value>
int HashMap<Key, Value>::TotalElems()
{
    return totElems;
}/* End of TotalElems */

template <class Key, class Value>
int HashMap<Key, Value>::BucketSize(int keyIndex)
{
    return(!IsEmpty(keyIndex)) ? bucketSize[keyIndex]:0;
}/* End of BucketSize */

template <class Key, class Value>
int HashMap<Key, Value>::Count(Key m_key, Value searchItem)
{
    int keyIndex = Hash(m_key);
    int search = 0;

    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nCOUNT ERROR - HASH MAP EMPTY\n";
    }
    else
    {
        for(node* temp = head[keyIndex];temp!=NULL;temp=temp->next)
        {
            if(temp->currentItem.key == m_key
                && temp->currentItem.value == searchItem)
            {
                ++search;
            }
        }
    }
    return search;
}/* End of Count */

template <class Key, class Value>
int HashMap<Key, Value>::ContainsKey(Key m_key)
{
    int keyIndex = Hash(m_key);
    int search = 0;

    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nCONTAINS KEY ERROR - HASH MAP EMPTY\n";
    }
    else
    {
        for(node* temp = head[keyIndex];temp!=NULL;temp=temp->next)
        {
            if(temp->currentItem.key == m_key)
            {
                ++search;
            }
        }
    }
    return search;
}/* End of ContainsKey */

template <class Key, class Value>
void HashMap<Key, Value>::MakeEmpty()
{
    totElems = 0;
    for(int x=0; x < hashSize; ++x)
    {
        if(!IsEmpty(x))
        {
            //std::cout << "Destroying nodes ...\n";
            while(!IsEmpty(x))
            {
                node* temp = head[x];
                //std::cout << temp-> currentItem.value <<std::endl;
                head[x] = head[x]-> next;
                delete temp;
            }
        }
        bucketSize[x] = 0;
    }
}/* End of MakeEmpty */

template <class Key, class Value>
HashMap<Key, Value>::~HashMap()
{
    MakeEmpty();
    delete[] head;
    delete[] bucketSize;
}/* End of ~HashMap */

//   END OF THE HASH MAP CLASS
// -----------------------------------------------------------
//   START OF THE HASH MAP ITERATOR CLASS

template <class Key, class Value>
class HashMap<Key, Value>::Iterator :
        public std::iterator<std::forward_iterator_tag,Value>,
        public HashMap<Key, Value>
    {
public:
    // Iterator constructor
    Iterator(node* otherIter = NULL)
    {
        itHead = otherIter;
    }
    ~Iterator() {}
    // The assignment and relational operators are straightforward
    Iterator& operator=(const Iterator& other)
    {
        itHead = other.itHead;
        return(*this);
    }
    bool operator==(const Iterator& other)const
    {
        return itHead == other.itHead;
    }
    bool operator!=(const Iterator& other)const
    {
        return itHead != other.itHead;
    }
    bool operator<(const Iterator& other)const
    {
        return itHead < other.itHead;
    }
    bool operator>(const Iterator& other)const
    {
        return other.itHead < itHead;
    }
    bool operator<=(const Iterator& other)const
    {
        return (!(other.itHead < itHead));
    }
    bool operator>=(const Iterator& other)const
    {
        return (!(itHead < other.itHead));
    }
    // Update my state such that I refer to the next element in the
    // HashMap.
    Iterator operator+(int incr)
    {
        node* temp = itHead;
        for(int x=0; x < incr && temp!= NULL; ++x)
        {
            temp = temp->next;
        }
        return temp;
    }
    Iterator operator+=(int incr)
    {
        for(int x=0; x < incr && itHead!= NULL; ++x)
        {
            itHead = itHead->next;
        }
        return itHead;
    }
    Iterator& operator++() // pre increment
    {
        if(itHead != NULL)
        {
            itHead = itHead->next;
        }
        return(*this);
    }
    Iterator operator++(int) // post increment
    {
        node* temp = itHead;
        this->operator++();
        return temp;
    }
    KeyValue& operator[](int incr)
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL || (*this + incr) == NULL)
        {
            return junk;
        }
        return(*(*this + incr));
    }
    // Return a reference to the value in the node.  I do this instead
    // of returning by value so a caller can update the value in the
    // node directly.
    KeyValue& operator*()
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL)
        {
            return junk;
        }
        return itHead->currentItem;
    }
    KeyValue* operator->()
    {
        return(&**this);
    }
private:
    node* itHead;
    KeyValue junk;
};
#endif // http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   June 11, 2013
//    Taken From: http://programmingnotes.org/
//    File:  HashMap.h
//    Description: This is a class which implements various functions
//          demonstrating the use of a Hash Map.
// ============================================================================
#ifndef TEMPLATE_HASH_MAP
#define TEMPLATE_HASH_MAP
#include <iostream>
#include <string>
#include <sstream>
#include <cstdlib>
 
// if user doesnt define, this is the
// default hash map size
const int HASH_SIZE = 350;
 
template <class Key, class Value>
class HashMap
{
public:
    HashMap(int hashSze = HASH_SIZE);
        /*   Function: Constructor initializes hash map
            Precondition: None
            Postcondition: Defines private variables */
    bool IsEmpty(int keyIndex);
        /*   Function: Determines whether hash map is empty at the given hash
                            map key index
            Precondition: Hash map has been created
            Postcondition: The function = true if the hash map is empty and the
                             function = false if hash map is not empty */
    bool  IsFull();
        /*   Function: Determines whether hash map is full
            Precondition: Hash map has been created
            Postcondition: The function = true if the hash map is full and the
                             function = false if hash map is not full */
    int Hash(Key m_key);
        /*   Function: Computes and returns a hash map key index for a given item
                        The returned key index is the given cell where the item resides
            Precondition:  Hash map has been created and is not full
            Postcondition: The hash key is returned */
    void Insert(Key m_key, Value m_value);
        /*   Function: Adds new item to the back of the list at a given key in the hash map
                         A unique hash key is automatically generated for each new item
            Precondition:  Hash map has been created and is not full
            Postcondition: Item is in the hash map */
    bool Remove(Key m_key, Value deleteItem);
        /*   Function: Removes the first instance from the map whose value is "deleteItem"
            Precondition:  Hash map has been created and is not empty
            Postcondition: The function = true if deleteItem is found and the
                             function = false if deleteItem is not found */
    void Sort(int keyIndex);
        /*   Function: Sort the items in the map at the given hashmap key index
            Precondition: Hash map has been initialized
            Postcondition: The hash map is sorted */
    int TableSize();
        /*   Function: Return the size of the hash map
            Precondition: Hash map has been initialized
            Postcondition: The size of the hash map is returned */
    int TotalElems();
        /*   Function: Return the total number of elements contained in the hash map
            Precondition: Hash map has been initialized
            Postcondition: The size of the hash map is returned */
    int BucketSize(int keyIndex);
        /*   Function: Return the number of items contained in the hash map
                        cell at the given hashmap key index
            Precondition: Hash map has been initialized
            Postcondition: The size of the given key cell is returned */
    int Count(Key m_key, Value searchItem);
        /*   Function: Return the number of times searchItem appears in the map
                        at the given key
            Precondition: Hash map has been initialized
            Postcondition: The number of times searchItem appears in the map is returned */
    int ContainsKey(Key m_key);
        /*   Function: Return the number of times the given key appears in the hashmap
            Precondition: Hash map has been initialized
            Postcondition: The number of times the given key appears in the map is returned */
    void MakeEmpty();
        /*   Function: Initializes hash map to an empty state
            Precondition: Hash map has been created
            Postcondition: Hash map no longer exists */
    ~HashMap();
        /*   Function: Removes the hash map
            Precondition: Hash map has been declared
            Postcondition: Hash map no longer exists */
 
    //  -- ITERATOR CLASS --
    class Iterator;
        /*   Function: Class declaration to the iterator
            Precondition: Hash map has been declared
            Postcondition: Hash Iterator has been declared */
 
    Iterator begin(int keyIndex){return(!IsEmpty(keyIndex)) ? head[keyIndex]:NULL;}
        /*   Function: Returns the beginning of the current hashmap key index
            Precondition: Hash map has been declared
            Postcondition: Hash cell has been returned to the Iterator */
 
    Iterator end(int keyIndex=0){return NULL;}
        /*   Function: Returns the end of the current hashmap key index
            Precondition: Hash map has been declared
            Postcondition: Hash cell has been returned to the Iterator */
 
private:
    struct KeyValue  // struct to hold key/value pairs
    {
        Key key;
        Value value;
    };
    struct node
    {
        KeyValue currentItem;
        node* next;
    };
    node** head; // array of linked list declaration - front of each hash map cell
    int hashSize; // the size of the hash map (how many cells it has)
    int totElems; // holds the total number of elements in the entire table
    int* bucketSize; // holds the total number of elems in each specific hash map cell
};
 
//=========================  Implementation  ================================//
 
template <class Key, class Value>
HashMap<Key, Value>::HashMap(int hashSze)
{
    hashSize = hashSze;
    head = new node*[hashSize];
    bucketSize = new int[hashSize];
    for(int x=0; x < hashSize; ++x)
    {
        head[x] = NULL;
        bucketSize[x] = 0;
    }
    totElems = 0;
}/* End of HashMap */
 
template <class Key, class Value>
bool HashMap<Key, Value>::IsEmpty(int keyIndex)
{
    if(keyIndex >=0 && keyIndex < hashSize)
    {
        return head[keyIndex] == NULL;
    }
    return true;
}/* End of IsEmpty */
 
template <class Key, class Value>
bool HashMap<Key, Value>::IsFull()
{
    try
    {
        node* location = new node;
        delete location;
        return false;
    }
    catch(std::bad_alloc&)
    {
        return true;
    }
}/* End of IsFull */
 
template <class Key, class Value>
int HashMap<Key, Value>::Hash(Key m_key)
{
    long h = 19937;
    std::stringstream convert;
 
    // convert the parameter to a string using "stringstream" which is done
    // so we can hash multiple datatypes using only one function
    convert << m_key;
    std::string temp = convert.str();
 
    for(unsigned x=0; x < temp.length(); ++x)
    {
        h = (h << 6) ^ (h >> 26) ^ temp[x];
    }
    return abs(h % hashSize);
} /* End of Hash */
 
template <class Key, class Value>
void HashMap<Key, Value>::Insert(Key m_key, Value m_value)
{
    if(IsFull())
    {
        //std::cout<<"\nINSERT ERROR - HASH MAP FULL\n";
    }
    else
    {
        int keyIndex = Hash(m_key);
        node* newNode = new node;   // add new node
        newNode-> currentItem.key = m_key;
        newNode-> currentItem.value = m_value;
        newNode-> next = NULL;
 
        if(IsEmpty(keyIndex))
        {
            head[keyIndex] = newNode;
        }
        else
        {
            node* temp = head[keyIndex];
            while(temp-> next != NULL)
            {
                temp = temp-> next;
            }
            temp-> next = newNode;
        }
        ++bucketSize[keyIndex];
        ++totElems;
    }
}/* End of Insert */
 
template <class Key, class Value>
bool HashMap<Key, Value>::Remove(Key m_key, Value deleteItem)
{
    bool isFound = false;
    node* temp;
    int keyIndex = Hash(m_key);
 
    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nREMOVE ERROR - HASH MAP EMPTY\n";
    }
    else if(head[keyIndex]->currentItem.key == m_key
            && head[keyIndex]->currentItem.value == deleteItem)
    {
        temp = head[keyIndex];
        head[keyIndex] = head[keyIndex]-> next;
        delete temp;
        --totElems;
        --bucketSize[keyIndex];
        isFound = true;
    }
    else
    {
        for(temp = head[keyIndex];temp->next!=NULL;temp=temp->next)
        {
            if(temp->next->currentItem.key == m_key
                && temp->next->currentItem.value == deleteItem)
            {
                node* deleteNode = temp->next;
                temp-> next = temp-> next-> next;
                delete deleteNode;
                isFound = true;
                --totElems;
                --bucketSize[keyIndex];
                break;
            }
        }
    }
    return isFound;
}/* End of Remove */
 
template <class Key, class Value>
void HashMap<Key, Value>::Sort(int keyIndex)
{
    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nSORT ERROR - HASH MAP EMPTY\n";
    }
    else
    {
        int listSize = BucketSize(keyIndex);
        bool sorted = false;
 
        do{
            sorted = true;
            int x = 0;
            for(node* temp = head[keyIndex];
                temp->next!=NULL && x < listSize-1;
                temp=temp->next,++x)
            {
                if(temp-> currentItem.value > temp->next->currentItem.value)
                {
                    std::swap(temp-> currentItem,temp->next->currentItem);
                    sorted = false;
                }
            }
            --listSize;
        }while(!sorted);
    }
}/* End of Sort */
 
template <class Key, class Value>
int HashMap<Key, Value>::TableSize()
{
    return hashSize;
}/* End of TableSize */
 
template <class Key, class Value>
int HashMap<Key, Value>::TotalElems()
{
    return totElems;
}/* End of TotalElems */
 
template <class Key, class Value>
int HashMap<Key, Value>::BucketSize(int keyIndex)
{
    return(!IsEmpty(keyIndex)) ? bucketSize[keyIndex]:0;
}/* End of BucketSize */
 
template <class Key, class Value>
int HashMap<Key, Value>::Count(Key m_key, Value searchItem)
{
    int keyIndex = Hash(m_key);
    int search = 0;
 
    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nCOUNT ERROR - HASH MAP EMPTY\n";
    }
    else
    {
        for(node* temp = head[keyIndex];temp!=NULL;temp=temp->next)
        {
            if(temp->currentItem.key == m_key
                && temp->currentItem.value == searchItem)
            {
                ++search;
            }
        }
    }
    return search;
}/* End of Count */
 
template <class Key, class Value>
int HashMap<Key, Value>::ContainsKey(Key m_key)
{
    int keyIndex = Hash(m_key);
    int search = 0;
 
    if(IsEmpty(keyIndex))
    {
        //std::cout<<"\nCONTAINS KEY ERROR - HASH MAP EMPTY\n";
    }
    else
    {
        for(node* temp = head[keyIndex];temp!=NULL;temp=temp->next)
        {
            if(temp->currentItem.key == m_key)
            {
                ++search;
            }
        }
    }
    return search;
}/* End of ContainsKey */
 
template <class Key, class Value>
void HashMap<Key, Value>::MakeEmpty()
{
    totElems = 0;
    for(int x=0; x < hashSize; ++x)
    {
        if(!IsEmpty(x))
        {
            //std::cout << "Destroying nodes ...\n";
            while(!IsEmpty(x))
            {
                node* temp = head[x];
                //std::cout << temp-> currentItem.value <<std::endl;
                head[x] = head[x]-> next;
                delete temp;
            }
        }
        bucketSize[x] = 0;
    }
}/* End of MakeEmpty */
 
template <class Key, class Value>
HashMap<Key, Value>::~HashMap()
{
    MakeEmpty();
    delete[] head;
    delete[] bucketSize;
}/* End of ~HashMap */
 
//   END OF THE HASH MAP CLASS
// -----------------------------------------------------------
//   START OF THE HASH MAP ITERATOR CLASS
 
template <class Key, class Value>
class HashMap<Key, Value>::Iterator :
        public std::iterator<std::forward_iterator_tag,Value>,
        public HashMap<Key, Value>
    {
public:
    // Iterator constructor
    Iterator(node* otherIter = NULL)
    {
        itHead = otherIter;
    }
    ~Iterator() {}
    // The assignment and relational operators are straightforward
    Iterator& operator=(const Iterator& other)
    {
        itHead = other.itHead;
        return(*this);
    }
    bool operator==(const Iterator& other)const
    {
        return itHead == other.itHead;
    }
    bool operator!=(const Iterator& other)const
    {
        return itHead != other.itHead;
    }
    bool operator<(const Iterator& other)const
    {
        return itHead < other.itHead;
    }
    bool operator>(const Iterator& other)const
    {
        return other.itHead < itHead;
    }
    bool operator<=(const Iterator& other)const
    {
        return (!(other.itHead < itHead));
    }
    bool operator>=(const Iterator& other)const
    {
        return (!(itHead < other.itHead));
    }
    // Update my state such that I refer to the next element in the
    // HashMap.
    Iterator operator+(int incr)
    {
        node* temp = itHead;
        for(int x=0; x < incr && temp!= NULL; ++x)
        {
            temp = temp->next;
        }
        return temp;
    }
    Iterator operator+=(int incr)
    {
        for(int x=0; x < incr && itHead!= NULL; ++x)
        {
            itHead = itHead->next;
        }
        return itHead;
    }
    Iterator& operator++() // pre increment
    {
        if(itHead != NULL)
        {
            itHead = itHead->next;
        }
        return(*this);
    }
    Iterator operator++(int) // post increment
    {
        node* temp = itHead;
        this->operator++();
        return temp;
    }
    KeyValue& operator[](int incr)
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL || (*this + incr) == NULL)
        {
            return junk;
        }
        return(*(*this + incr));
    }
    // Return a reference to the value in the node.  I do this instead
    // of returning by value so a caller can update the value in the
    // node directly.
    KeyValue& operator*()
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL)
        {
            return junk;
        }
        return itHead->currentItem;
    }
    KeyValue* operator->()
    {
        return(&**this);
    }
private:
    node* itHead;
    KeyValue junk;
};
#endif // http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The iterator class starts on line #381, and is built to support most of the standard relational operators, as well as arithmetic operators such as ‘+,+=,++’ (pre/post increment). The * (star), bracket [] and -> arrow operators are also supported. Click here for an overview demonstrating how custom iterators can be built.

The rest of the code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

===== DEMONSTRATION HOW TO USE =====

Use of the above template class is the same as many of its STL template class counterparts. Here are sample programs demonstrating its use.





		
		
			#1 - Demonstrate Basic Use
			
C++
			
			// DEMONSTRATE BASIC USE AND THE REMOVE / SORT FUNCTIONS
#include <iostream>
#include <string>
#include "HashMap.h"
using namespace std;

// iterator declaration
typedef HashMap<string, int>::Iterator iterDec;

int main()
{
    // declare variables
    HashMap<string, int> hashMap;
    
    // place items into the hash map using the 'insert' function
    // NOTE: its OK for dupicate keys to be inserted into the hash map
    hashMap.Insert("BIOL", 585);
    hashMap.Insert("CPSC", 386);
    hashMap.Insert("ART", 101);
    hashMap.Insert("CPSC", 462);
    hashMap.Insert("HIST", 251);
    hashMap.Insert("CPSC", 301);
    hashMap.Insert("MATH", 270);
    hashMap.Insert("PE", 145);
    hashMap.Insert("BIOL", 134);
    hashMap.Insert("GEOL", 201);
    hashMap.Insert("CIS", 465);
    hashMap.Insert("CPSC", 240);
    hashMap.Insert("GEOL", 101);
    hashMap.Insert("MATH", 150);
    hashMap.Insert("DANCE", 134);
    hashMap.Insert("CPSC", 131);
    hashMap.Insert("ART", 345);
    hashMap.Insert("CHEM", 185);
    hashMap.Insert("PE", 125);
    hashMap.Insert("CPSC", 120);
    
    // display the number of times the key "CPSC" appears in the hashmap
    cout<<"The key 'CPSC' appears in the hash map "<<
        hashMap.ContainsKey("CPSC")<<" time(s)\n";
    
    // declare an iterator for the "CPSC" key so we can display data to screen
    iterDec it = hashMap.begin(hashMap.Hash("CPSC"));
    
    // display the first value
    cout<<"\nThe first item with the key 'CPSC' is: "
        <<it[0].value<<endl;
    
    // display all the values in the hash map whose key matches "CPSC"
    // NOTE: its possible for multiple different keys types
    //   to be placed into the same hash map bucket    
    cout<<"\nThese are all the items in the hash map whose key is 'CPSC': \n";
    for(int x=0; x < hashMap.BucketSize(hashMap.Hash("CPSC")); ++x)
    {
        if(it[x].key == "CPSC") // make sure this is the key we are looking for
        {
            cout<<"  Key-> "<<it[x].key<<"\tValue-> "<<it[x].value<<endl;
        }
    }
    
    // remove the first value from the key "CPSC"
    cout<<"\n[REMOVE THE VALUE '"<<it[0].value<<"' FROM THE KEY '"<<it[0].key<<"']\n";    
    hashMap.Remove("CPSC",it[0].value);
    
    // display the number of times the key "CPSC" appears in the hashmap
    cout<<"\nNow the key 'CPSC' only appears in the hash map "<<
        hashMap.ContainsKey("CPSC")<<" time(s)\n";     
    
    // update the iterator to the current hash map state
    it = hashMap.begin(hashMap.Hash("CPSC"));
    
    // sort the values in the hash map bucket whose key is "CSPC"
    hashMap.Sort(hashMap.Hash("CPSC"));
    
    // display the values whose key matches "CPSC"
    cout<<"\nThese are the sorted items in the hash map whose key is 'CPSC': \n";
    for(int x=0; x < hashMap.BucketSize(hashMap.Hash("CPSC")); ++x)
    {
        if(it[x].key == "CPSC")
        {
            cout<<"  Key-> "<<it[x].key<<"\tValue-> "<<it[x].value<<endl;
        }
    }        
        
    // display all the key/values in the entire hash map 
    cout<<"\nThese are all of the items in the entire hash map: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            for(iterDec iter = hashMap.begin(x); iter != hashMap.end(x); ++iter)
            {
                cout<<"  Key-> "<<(*iter).key<<"\tValue-> "<<iter->value<<endl;
            }
            cout<<endl;
        }        
    }
    
    // display the total number of items in the hash map
    cout<<"The total number of items in the hash map is: "<<
        hashMap.TotalElems()<<endl;           
    
    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// DEMONSTRATE BASIC USE AND THE REMOVE / SORT FUNCTIONS
#include <iostream>
#include <string>
#include "HashMap.h"
using namespace std;
 
// iterator declaration
typedef HashMap<string, int>::Iterator iterDec;
 
int main()
{
    // declare variables
    HashMap<string, int> hashMap;
    
    // place items into the hash map using the 'insert' function
    // NOTE: its OK for dupicate keys to be inserted into the hash map
    hashMap.Insert("BIOL", 585);
    hashMap.Insert("CPSC", 386);
    hashMap.Insert("ART", 101);
    hashMap.Insert("CPSC", 462);
    hashMap.Insert("HIST", 251);
    hashMap.Insert("CPSC", 301);
    hashMap.Insert("MATH", 270);
    hashMap.Insert("PE", 145);
    hashMap.Insert("BIOL", 134);
    hashMap.Insert("GEOL", 201);
    hashMap.Insert("CIS", 465);
    hashMap.Insert("CPSC", 240);
    hashMap.Insert("GEOL", 101);
    hashMap.Insert("MATH", 150);
    hashMap.Insert("DANCE", 134);
    hashMap.Insert("CPSC", 131);
    hashMap.Insert("ART", 345);
    hashMap.Insert("CHEM", 185);
    hashMap.Insert("PE", 125);
    hashMap.Insert("CPSC", 120);
    
    // display the number of times the key "CPSC" appears in the hashmap
    cout<<"The key 'CPSC' appears in the hash map "<<
        hashMap.ContainsKey("CPSC")<<" time(s)\n";
    
    // declare an iterator for the "CPSC" key so we can display data to screen
    iterDec it = hashMap.begin(hashMap.Hash("CPSC"));
    
    // display the first value
    cout<<"\nThe first item with the key 'CPSC' is: "
        <<it[0].value<<endl;
    
    // display all the values in the hash map whose key matches "CPSC"
    // NOTE: its possible for multiple different keys types
    //   to be placed into the same hash map bucket    
    cout<<"\nThese are all the items in the hash map whose key is 'CPSC': \n";
    for(int x=0; x < hashMap.BucketSize(hashMap.Hash("CPSC")); ++x)
    {
        if(it[x].key == "CPSC") // make sure this is the key we are looking for
        {
            cout<<"  Key-> "<<it[x].key<<"\tValue-> "<<it[x].value<<endl;
        }
    }
    
    // remove the first value from the key "CPSC"
    cout<<"\n[REMOVE THE VALUE '"<<it[0].value<<"' FROM THE KEY '"<<it[0].key<<"']\n";    
    hashMap.Remove("CPSC",it[0].value);
    
    // display the number of times the key "CPSC" appears in the hashmap
    cout<<"\nNow the key 'CPSC' only appears in the hash map "<<
        hashMap.ContainsKey("CPSC")<<" time(s)\n";     
    
    // update the iterator to the current hash map state
    it = hashMap.begin(hashMap.Hash("CPSC"));
    
    // sort the values in the hash map bucket whose key is "CSPC"
    hashMap.Sort(hashMap.Hash("CPSC"));
    
    // display the values whose key matches "CPSC"
    cout<<"\nThese are the sorted items in the hash map whose key is 'CPSC': \n";
    for(int x=0; x < hashMap.BucketSize(hashMap.Hash("CPSC")); ++x)
    {
        if(it[x].key == "CPSC")
        {
            cout<<"  Key-> "<<it[x].key<<"\tValue-> "<<it[x].value<<endl;
        }
    }        
        
    // display all the key/values in the entire hash map 
    cout<<"\nThese are all of the items in the entire hash map: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            for(iterDec iter = hashMap.begin(x); iter != hashMap.end(x); ++iter)
            {
                cout<<"  Key-> "<<(*iter).key<<"\tValue-> "<<iter->value<<endl;
            }
            cout<<endl;
        }        
    }
    
    // display the total number of items in the hash map
    cout<<"The total number of items in the hash map is: "<<
        hashMap.TotalElems()<<endl;           
    
    return 0;
}// http://programmingnotes.org/

SAMPLE OUTPUT:

The key 'CPSC' appears in the hash map 6 time(s)
The first item with the key 'CPSC' is: 386 These are all the items in the hash map whose key is 'CPSC': Key-> CPSC Value-> 386 Key-> CPSC Value-> 462 Key-> CPSC Value-> 301 Key-> CPSC Value-> 240 Key-> CPSC Value-> 131 Key-> CPSC Value-> 120 [REMOVE THE VALUE '386' FROM THE KEY 'CPSC'] Now the key 'CPSC' only appears in the hash map 5 time(s) These are the sorted items in the hash map whose key is 'CPSC': Key-> CPSC Value-> 120 Key-> CPSC Value-> 131 Key-> CPSC Value-> 240 Key-> CPSC Value-> 301 Key-> CPSC Value-> 462 These are all of the items in the entire hash map: Key-> CIS Value-> 465 Key-> DANCE Value-> 134 Key-> PE Value-> 145 Key-> PE Value-> 125 Key-> MATH Value-> 270 Key-> MATH Value-> 150 Key-> GEOL Value-> 201 Key-> GEOL Value-> 101 Key-> CPSC Value-> 120 Key-> CPSC Value-> 131 Key-> CPSC Value-> 240 Key-> CPSC Value-> 301 Key-> CPSC Value-> 462 Key-> BIOL Value-> 585 Key-> BIOL Value-> 134 Key-> ART Value-> 101 Key-> ART Value-> 345 Key-> CHEM Value-> 185 Key-> HIST Value-> 251
The total number of items in the hash map is: 19





		
		
			#2 - Display Items In A Struct
			
C++
			
			// DISPLAY ALL DATA INSIDE HASH MAP USING STD::STRING / INT / DOUBLE / STRUCT
#include <iostream>
#include <string>
#include "HashMap.h"
using namespace std;

// sample struct demo
struct MyStruct
{
    string car;
    int year;
    double mpg;
    
    // struct comparison operators
    // used for 'remove' function
    bool operator == (const MyStruct& rhs)const
    {
        return car == rhs.car &&
            year == rhs.year &&
            mpg == rhs.mpg;
    }    
    // used for 'sort' function
    bool operator > (const MyStruct& rhs)const
    {
        return car > rhs.car;
    }    
};// end of MyStruct

// iterator declaration
typedef HashMap<string, MyStruct>::Iterator iterDec;

int main()
{
    // declare variables
    MyStruct access; 
    HashMap<string, MyStruct> hashMap(10);
    
    // --- initialize data for car #1 ---
    access.car = "Ford Fusion";
    access.year = 2006;
    access.mpg = 28.5;        
    hashMap.Insert("Kenneth",access);            
    
    // --- initialize data for car #2 ---
    access.car = "BMW 535i";
    access.year = 2014;
    access.mpg = 25.4;
    hashMap.Insert("Kenneth",access);
    
    // --- initialize data for car #3 ---
    access.car = "Nissan Altima";
    access.year = 2011;
    access.mpg = 30.7;
    hashMap.Insert("Jessica",access);     
    
    // --- initialize data for car #4 ---
    access.car = "Acura Integra";
    access.year = 2001;
    access.mpg = 20.2;    
    hashMap.Insert("Kenneth",access);       
    
    
    // diplay how many cars "Kenneth" owns
    cout <<"'Kenneth' owns "<<hashMap.ContainsKey("Kenneth")<<" cars"<<endl;             
    
    // display all items in the hash map
    // NOTE: its possible for multiple different keys types
    //   to be placed into the same hash map bucket     
    cout<<"\nThese are all of the cars in the hash map: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            // initialize an iterator
            iterDec iter = hashMap.begin(x);
            
            // display the key
            cout<<(*iter).key<<"'s car(s)\n";
            // display all the values 
            for(;iter != hashMap.end(x); ++iter)
            {
                cout<<"\tCar: "<<iter->value.car
                    <<"\n\tYear: "<<iter->value.year
                    <<"\n\tMPG: "<<iter->value.mpg<<endl<<endl;                                
            }
        }        
    }               
    
    // display the number of items in the hash map
    cout<<"The total number of cars in the hash map is: "<<
        hashMap.TotalElems()<<endl;   
    
    // sort the cars that "Kenneth" owns by name
    cout<<"\nSorting the cars that 'Kenneth' owns by name.. \n";         
    hashMap.Sort(hashMap.Hash("Kenneth"));    
    
    // display all items in the hash map again  
    cout<<"\nAgain, these are all of the cars in the hash map: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            // initialize an iterator
            iterDec iter = hashMap.begin(x);
            
            // display the key
            cout<<iter->key<<"'s car(s)\n";
            // display all the values 
            for(;iter != hashMap.end(x); ++iter)
            {
                cout<<"\tCar: "<<(*iter).value.car
                    <<"\n\tYear: "<<(*iter).value.year
                    <<"\n\tMPG: "<<(*iter).value.mpg<<endl<<endl;                
            }
        }        
    } 

    // remove the car 'Acura Integra' from "Kenneth's" inventory
    for(iterDec iter = hashMap.begin(hashMap.Hash("Kenneth")); 
        iter != hashMap.end(hashMap.Hash("Kenneth")); ++iter)
    {		
        if(iter->value.car == "Acura Integra")
        {
            cout<<"'"<<iter->value.car<<"' has been removed from 'Kenneth's' inventory..\n";
            hashMap.Remove("Kenneth",(*iter).value);
            break;
        }
    }    
    
    // display how many cars "Kenneth" owns
    cout <<"\n'Kenneth' now owns only "<<hashMap.ContainsKey("Kenneth")<<" cars"<<endl;                 
    
    // display all items in the hash map one more time  
    cout<<"\nThese are all of the cars in the hash map with the 'Acura Integra' removed: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            // initialize an iterator
            iterDec iter = hashMap.begin(x);
            
            // display the key
            cout<<(*iter).key<<"'s car(s)\n";
            // display all the values 
            for(;iter != hashMap.end(x); ++iter)
            {
                cout<<"\tCar: "<<iter->value.car
                    <<"\n\tYear: "<<iter->value.year
                    <<"\n\tMPG: "<<iter->value.mpg<<endl<<endl;
            }
        }        
    }     
    
    // display the number of items in the hash map
    cout<<"The total number of cars in the hash map is: "<<
        hashMap.TotalElems()<<endl;               
    
    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// DISPLAY ALL DATA INSIDE HASH MAP USING STD::STRING / INT / DOUBLE / STRUCT
#include <iostream>
#include <string>
#include "HashMap.h"
using namespace std;
 
// sample struct demo
struct MyStruct
{
    string car;
    int year;
    double mpg;
    
    // struct comparison operators
    // used for 'remove' function
    bool operator == (const MyStruct& rhs)const
    {
        return car == rhs.car &&
            year == rhs.year &&
            mpg == rhs.mpg;
    }    
    // used for 'sort' function
    bool operator > (const MyStruct& rhs)const
    {
        return car > rhs.car;
    }    
};// end of MyStruct
 
// iterator declaration
typedef HashMap<string, MyStruct>::Iterator iterDec;
 
int main()
{
    // declare variables
    MyStruct access; 
    HashMap<string, MyStruct> hashMap(10);
    
    // --- initialize data for car #1 ---
    access.car = "Ford Fusion";
    access.year = 2006;
    access.mpg = 28.5;        
    hashMap.Insert("Kenneth",access);            
    
    // --- initialize data for car #2 ---
    access.car = "BMW 535i";
    access.year = 2014;
    access.mpg = 25.4;
    hashMap.Insert("Kenneth",access);
    
    // --- initialize data for car #3 ---
    access.car = "Nissan Altima";
    access.year = 2011;
    access.mpg = 30.7;
    hashMap.Insert("Jessica",access);     
    
    // --- initialize data for car #4 ---
    access.car = "Acura Integra";
    access.year = 2001;
    access.mpg = 20.2;    
    hashMap.Insert("Kenneth",access);       
    
    
    // diplay how many cars "Kenneth" owns
    cout <<"'Kenneth' owns "<<hashMap.ContainsKey("Kenneth")<<" cars"<<endl;             
    
    // display all items in the hash map
    // NOTE: its possible for multiple different keys types
    //   to be placed into the same hash map bucket     
    cout<<"\nThese are all of the cars in the hash map: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            // initialize an iterator
            iterDec iter = hashMap.begin(x);
            
            // display the key
            cout<<(*iter).key<<"'s car(s)\n";
            // display all the values 
            for(;iter != hashMap.end(x); ++iter)
            {
                cout<<"\tCar: "<<iter->value.car
                    <<"\n\tYear: "<<iter->value.year
                    <<"\n\tMPG: "<<iter->value.mpg<<endl<<endl;                                
            }
        }        
    }               
    
    // display the number of items in the hash map
    cout<<"The total number of cars in the hash map is: "<<
        hashMap.TotalElems()<<endl;   
    
    // sort the cars that "Kenneth" owns by name
    cout<<"\nSorting the cars that 'Kenneth' owns by name.. \n";         
    hashMap.Sort(hashMap.Hash("Kenneth"));    
    
    // display all items in the hash map again  
    cout<<"\nAgain, these are all of the cars in the hash map: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            // initialize an iterator
            iterDec iter = hashMap.begin(x);
            
            // display the key
            cout<<iter->key<<"'s car(s)\n";
            // display all the values 
            for(;iter != hashMap.end(x); ++iter)
            {
                cout<<"\tCar: "<<(*iter).value.car
                    <<"\n\tYear: "<<(*iter).value.year
                    <<"\n\tMPG: "<<(*iter).value.mpg<<endl<<endl;                
            }
        }        
    } 
 
    // remove the car 'Acura Integra' from "Kenneth's" inventory
    for(iterDec iter = hashMap.begin(hashMap.Hash("Kenneth")); 
        iter != hashMap.end(hashMap.Hash("Kenneth")); ++iter)
    {		
        if(iter->value.car == "Acura Integra")
        {
            cout<<"'"<<iter->value.car<<"' has been removed from 'Kenneth's' inventory..\n";
            hashMap.Remove("Kenneth",(*iter).value);
            break;
        }
    }    
    
    // display how many cars "Kenneth" owns
    cout <<"\n'Kenneth' now owns only "<<hashMap.ContainsKey("Kenneth")<<" cars"<<endl;                 
    
    // display all items in the hash map one more time  
    cout<<"\nThese are all of the cars in the hash map with the 'Acura Integra' removed: \n";
    for(int x=0; x < hashMap.TableSize(); ++x)
    {
        if(!hashMap.IsEmpty(x))
        {
            // initialize an iterator
            iterDec iter = hashMap.begin(x);
            
            // display the key
            cout<<(*iter).key<<"'s car(s)\n";
            // display all the values 
            for(;iter != hashMap.end(x); ++iter)
            {
                cout<<"\tCar: "<<iter->value.car
                    <<"\n\tYear: "<<iter->value.year
                    <<"\n\tMPG: "<<iter->value.mpg<<endl<<endl;
            }
        }        
    }     
    
    // display the number of items in the hash map
    cout<<"The total number of cars in the hash map is: "<<
        hashMap.TotalElems()<<endl;               
    
    return 0;
}// http://programmingnotes.org/

SAMPLE OUTPUT:

'Kenneth' owns 3 cars
These are all of the cars in the hash map: Jessica's car(s) Car: Nissan Altima Year: 2011 MPG: 30.7 Kenneth's car(s) Car: Ford Fusion Year: 2006 MPG: 28.5 Car: BMW 535i Year: 2014 MPG: 25.4 Car: Acura Integra Year: 2001 MPG: 20.2 ----------------------------------------------------- The total number of cars in the hash map is: 4 Sorting the cars that 'Kenneth' owns by name.. Again, these are all of the cars in the hash map: Jessica's car(s) Car: Nissan Altima Year: 2011 MPG: 30.7 Kenneth's car(s) Car: Acura Integra Year: 2001 MPG: 20.2 Car: BMW 535i Year: 2014 MPG: 25.4 Car: Ford Fusion Year: 2006 MPG: 28.5 ----------------------------------------------------- 'Acura Integra' has been removed from 'Kenneth's' inventory.. 'Kenneth' now owns only 2 cars These are all of the cars in the hash map with the 'Acura Integra' removed: Jessica's car(s) Car: Nissan Altima Year: 2011 MPG: 30.7 Kenneth's car(s) Car: BMW 535i Year: 2014 MPG: 25.4 Car: Ford Fusion Year: 2006 MPG: 28.5 -----------------------------------------------------
The total number of cars in the hash map is: 3

Python || Using If Statements & String Variables

May 29, 2013 admin No comments

As previously mentioned, you can use “int” and “float” to represent numbers, but what if you want to store letters? Strings help you do that.

==== SINGLE CHAR ====

This example will demonstrate a simple program using strings, which checks to see if the user entered the correctly predefined letter.





		
		
			#1 - Guess a letter
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  char.py
#    Description: Demonstrates using char variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character

    # get data from user
    userInput = input("Please try to guess the letter I am thinking of: ")

    # we only want to check the first character in the string,
    # so we get the letter at index zero and save it into its
    # own variable
    letter = userInput[0]

    # use an if statement to check equality.
    if ((letter == 'a') or (letter == 'A')):
        print("\nYou have guessed correctly!")
    else:
        print("\nSorry, that was not the correct letter I was thinking of..")

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  char.py
#    Description: Demonstrates using char variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character
 
    # get data from user
    userInput = input("Please try to guess the letter I am thinking of: ")
 
    # we only want to check the first character in the string,
    # so we get the letter at index zero and save it into its
    # own variable
    letter = userInput[0]
 
    # use an if statement to check equality.
    if ((letter == 'a') or (letter == 'A')):
        print("\nYou have guessed correctly!")
    else:
        print("\nSorry, that was not the correct letter I was thinking of..")
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

Notice in line 11 I declare the string data type, naming it “userInput.” I also initialized it as an empty variable. In line 23 I used an “If/Else Statement” to determine if the user entered value matches the predefined letter within the program. I also used the “OR” operator in line 23 to determine if the letter the user entered into the program was lower or uppercase. Try compiling the program simply using this
if (letter == 'a') as your if statement, and notice the difference.

The resulting code should give this as output

Please try to guess the letter I am thinking of: A You have guessed correctly!

==== CHECK IF LETTER IS UPPER CASE ====

This example is similar to the previous one, and will check if a user entered letter is uppercase.





		
		
			#2 - Is Input Uppercase?
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  uppercase.py
#    Description: Demonstrates checking if a char variable is uppercase
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character

    # get data from user
    userInput = input("Please enter an UPPERCASE letter: ")

    # get the 1st character in the string
    letter = userInput[0]

    # check to see if entered data falls between uppercase values
    if ((letter >= 'A') and (letter <= 'Z')):
        print("\n'%c' is an is an uppercase letter!" % (letter))
    else:
        print("\nSorry, '%c' is not an uppercase letter.." % (letter))

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  uppercase.py
#    Description: Demonstrates checking if a char variable is uppercase
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character
 
    # get data from user
    userInput = input("Please enter an UPPERCASE letter: ")
 
    # get the 1st character in the string
    letter = userInput[0]
 
    # check to see if entered data falls between uppercase values
    if ((letter >= 'A') and (letter <= 'Z')):
        print("\n'%c' is an is an uppercase letter!" % (letter))
    else:
        print("\nSorry, '%c' is not an uppercase letter.." % (letter))
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

Notice in line 21, an If statement was used, which checks to see if the user entered data falls between letter A and letter Z. We did that by using the “AND” operator. So that IF statement is basically saying (in plain english)

IF ('letter' is equal to or greater than 'A') AND ('letter' is equal to or less than 'Z')
THEN it is an uppercase letter

The resulting code should give this as output

Please enter an UPPERCASE letter: g Sorry, 'g' is not an uppercase letter..

==== CHECK IF LETTER IS A VOWEL ====

This example will utilize more if statements, checking to see if the user entered letter is a vowel or not. This will be very similar to the previous example, utilizing the OR operator once again.





		
		
			#3 - Is Input a Vowel?
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  vowel.py
#    Description: Demonstrates checking if a char variable is a vowel
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character

    # get data from user
    userInput = input("Please enter a vowel: ")

    # get the 1st character in the string
    letter = userInput[0]

    # check to see if entered data is A,E,I,O,U,Y
    if ((letter == 'a')or(letter == 'A')or(letter == 'e')or
        (letter == 'E')or(letter == 'i')or(letter == 'I')or
        (letter == 'o')or(letter == 'O')or(letter == 'u')or
        (letter == 'U')or(letter == 'y')or(letter == 'Y')):
        print("\nCorrect, '%c' is a vowel!" % (letter))
    else:
        print("\nSorry, '%c' is not a vowel.." % (letter))

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  vowel.py
#    Description: Demonstrates checking if a char variable is a vowel
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character
 
    # get data from user
    userInput = input("Please enter a vowel: ")
 
    # get the 1st character in the string
    letter = userInput[0]
 
    # check to see if entered data is A,E,I,O,U,Y
    if ((letter == 'a')or(letter == 'A')or(letter == 'e')or
        (letter == 'E')or(letter == 'i')or(letter == 'I')or
        (letter == 'o')or(letter == 'O')or(letter == 'u')or
        (letter == 'U')or(letter == 'y')or(letter == 'Y')):
        print("\nCorrect, '%c' is a vowel!" % (letter))
    else:
        print("\nSorry, '%c' is not a vowel.." % (letter))
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

This program should be very straight forward, and its basically checking to see if the user entered data is the letter A, E, I, O, U or Y.

The resulting code should give the following output

Please enter a vowel: K Sorry, 'K' is not a vowel..

==== HELLO WORLD v2 ====

This last example will demonstrate using the string data type to print the line “Hello World!” to the screen.





		
		
			#4 - Hello World - String Version
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  string.py
#    Description: Demonstrates using string variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string

    # get data from user
    userInput = input("Please enter a sentence: ")

    # display string
    print("\nYou Entered: '%s'" % (userInput))

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  string.py
#    Description: Demonstrates using string variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
 
    # get data from user
    userInput = input("Please enter a sentence: ")
 
    # display string
    print("\nYou Entered: '%s'" % (userInput))
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

The following is similar to the other examples listed on this page, except we display the entire string instead of just simply the first character.

The resulting code should give following output

Please enter a sentence: Hello World! You Entered: 'Hello World!'

C++ || Simple Spell Checker Using A Hash Table

January 31, 2013 admin 4 Comments

Click Here For Updated Version Of Program

The following is another programming assignment which was presented in a C++ Data Structures course. This assignment was used to gain more experience using hash tables.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Hash Table - What Is It? How To Create A Spell Checker How To Read Data From A File Strtok - Split Strings Into Tokens #include 'HashTable.h' The Dictionary File - Download Here

== OVERVIEW ==

This program first reads words from a dictionary file, and inserts them into a hash table.

The dictionary file consists of a list of 62,454 correctly spelled lowercase words, separated by whitespace. The words are inserted into the hash table, with each bucket growing dynamically as necessary to hold all of the incoming data.

After the reading of the dictionary file is complete, the program prompts the user for input. After input is obtained, each word that the user enteres into the program is looked up within the hash table to see if it exists. If the user entered word exists within the hash table, then that word is spelled correctly. If not, a list of possible suggested spelling corrections is displayed to the screen.

== HASH TABLE STATISTICS ==

To better understand how hash tables work, this program reports the following statistics to the screen:

• The total size of the hash table. • The size of the largest hash table bucket. • The size of the smallest hash table bucket. • The total number of buckets used. • The average hash table bucket size.

A timer is used in this program to time (in seconds) how long it takes to read in the dictionary file. The program also saves each hash table bucket into a separate output .txt file. This is used to further visualize how the hash table data is internally being stored within memory.

== SPELL CHECKING ==

The easiest way to generate corrections for a spell checker is via a trial and error method. If we assume that the misspelled word contains only a single error, we can try all possible corrections and look each up in the dictionary.

Example:

wird: bird gird ward word wild wind wire wiry

Traditionally, spell checkers look for four possible errors: a wrong letter (“wird”), also knows as alteration. An inserted letter (“woprd”), a deleted letter (“wrd”), or a pair of adjacent transposed letters (“wrod”).

The easiest of which is checking for a wrong letter. For example, if a word isnt found in the dictionary, all variants of that word can be looked up by changing one letter. Given the user input “wird,” a one letter variant can be “aird”, “bird”, “cird”, etc. through “zird.” Then “ward”, “wbrd”, “wcrd” through “wzrd”, can be checked, and so forth. Whenever a match is found within the dictionary, the spelling correction should be displayed to the screen.

For a detailed analysis how the other methods can be constructed, click here.

===== SIMPLE SPELL CHECKER =====

This program uses a custom template.h class. To obtain the code for that class, click here.





		
		
			Simple Spell Checker Using A Hash Table
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 31, 2013
//    Taken From: http://programmingnotes.org/
//    File:  SpellCheck.cpp
//    Description: This is a simple spell checker which tests the HashTable.h
//          class. 
// ============================================================================
#include <iostream>
#include <fstream>
#include <cctype>
#include <cstring>
#include <string>
#include <iomanip>
#include <ctime>
#include <limits>
#include "HashTable.h"
using namespace std;

// iterator declaration for hash table
typedef HashTable<string>::Iterator iterDec;
 
// hash table size
const int TABLE_SIZE = 19000;

// strtok delimiters
const char* DELIMITERS = " ,.-\':;?()+*/\\%$#!\"@\^&";

// function prototypes
void PrintTableStats(HashTable<string>& hashTable);
int SpellCheck(HashTable<string>& hashTable, string word);
string ToLowerCase(string word);

int main()
{	
	// declare variables
	int result = 0;
	string userInput;
	string currWord;
	clock_t beg; // used to time the hashtable load
	clock_t end; // used to time the hashtable load
	char response;
	ifstream infile;
	HashTable<string> hashTable(TABLE_SIZE);

	// open the dictionary file
	infile.open("INPUT_Dictionary_programmingnotes_freeweq_com.txt");

	// check if the file exists, EXIT if it doesnt
	if(infile.fail())
	{
		cout<<"\n\n**ERROR - The dictionary file could not be found...\n";
		exit(1);
	}

	cerr<<"\nLoading dictionary....";		
	beg = clock(); // start the timer

	// get data from file and put into hashtable
	while(infile >> currWord)
	{
		// makes sure duplicate words arent inserted into table
		if(!hashTable.Count(currWord))
		{
			hashTable.Insert(currWord);
		}
	}	
	infile.close();
	PrintTableStats(hashTable);	

	end = clock()-beg; // end the timer
	cout<<"\n\nDictionary loaded in "<<
		(double)end / ((double)CLOCKS_PER_SEC)<<" secs!";
	
	// creates a line separator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(50)<<""<<endl;	

	do{ // get user input
		cout<<"\n>> Please enter a sentence: ";	
		getline(cin,userInput);
		cout<<endl;

		// split each word from the string into individual words to check if 
		// they are spelled correctly 
		char* splitInput = strtok(const_cast<char*>(userInput.c_str()),DELIMITERS);
		while(splitInput!=NULL)
		{		
			currWord = splitInput;
			currWord = ToLowerCase(currWord);
			result += SpellCheck(hashTable,currWord);
			splitInput = strtok(NULL,DELIMITERS);
		}

		// display results		
		if(result > 0)
		{
			cout<<"Number of words spelled incorrectly: "<<result<<endl;
			result = 0;
		}

		// ask for more data
		cout<<"\nDo you want to enter another sentence? (y/n): ";
		cin >> response;
		cin.ignore(numeric_limits<streamsize>::max(),'\n'); // clear the cin buffer
	}while(toupper(response)=='Y');

	cout<<"\nBYE!!\n";

	return 0;
}// end of main

void PrintTableStats(HashTable<string>& hashTable)
{
	int largestBucket = -9999999;
	int largestIndex = 0;
	int smallestBucket = 9999999;
	int smallestIndex = 0;
	double numBuckestUsed = 0;
	ofstream outfile("OUTPUT_HashTable_Stats_programmingnotes_freeweq_com.txt");
	
	for(int x=0; x < hashTable.TableSize(); ++x)
	{
		// iterator is used to traverse each hashtable bucket
		iterDec it = hashTable.begin(x);
		if(!hashTable.IsEmpty(x))
		{
			if(smallestBucket > hashTable.BucketSize(x))
			{
				smallestBucket = hashTable.BucketSize(x);
				smallestIndex = x;
			}
			if(largestBucket < hashTable.BucketSize(x))
			{
				largestBucket = hashTable.BucketSize(x);
				largestIndex = x;
			}
			++numBuckestUsed;
			outfile<<"\nBucket #"<<x<<":\n";
			for(int y = 0; y < hashTable.BucketSize(x); ++y)
			{
				outfile <<"\t"<< it[y] << endl;
			}
		}
	}
	cout<<"Complete!\n";

	// creates a line separator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(50)<<""<<endl;

	cout<<"Total dictionary words = "<<hashTable.TotalElems()<<endl
		<<"Hash table size = "<<hashTable.TableSize()<<endl
		<<"Largest bucket size = "<<largestBucket<< " items at index #"<<largestIndex<<endl
		<<"Smallest bucket size = "<<smallestBucket<< " items at index #"<<smallestIndex<<endl
		<<"Total buckets used = "<<numBuckestUsed<<endl
		<<"Total percent of hash table used = "<<(numBuckestUsed/hashTable.TableSize())*100<<"%"<<endl
		<<"Average bucket size = "<<(hashTable.TotalElems()/numBuckestUsed)<<" items";
}// end of PrintTableStats

int SpellCheck(HashTable<string>& hashTable, string word)
{	
	int result = 0;
	int suggestion = 0;
	string remove[256];
	int numRemove=0;

	if(!hashTable.Count(word))
	{
		++result;
		cout<<"** "<<word<<": ";			
		// alteration & insertion
		for(unsigned x = 0; x < word.length(); ++x)
		{		
			string alteration = word;
			for(char c = 'a'; c <= 'z'; ++c)
			{
				//alteration
				alteration[x] = c;
				if(hashTable.Count(alteration))
				{
					cout<<alteration<<", ";
					remove[numRemove++] = alteration;
					++suggestion;
					// remove the entry so it isnt displayed multiple times
					hashTable.Remove(alteration);
				}
				//insertion
				string insertion = word.substr(0, x) + c + word.substr(x);
				if(hashTable.Count(insertion))
				{
					cout<<insertion<<", ";	
					remove[numRemove++] = insertion;
					++suggestion;
					// remove the entry so it isnt displayed multiple times
					hashTable.Remove(insertion);
				}
			}
		}
		// transposition & deletion	
		for(unsigned x = 0; x < word.length()-1;++x) 
		{
			// transposition 
			string transposition = word.substr(0,x) + word[x+1] + word[x] + word.substr(x+2);
			if(hashTable.Count(transposition))
			{
				cout<<transposition<<", ";
				remove[numRemove++] = transposition;
				++suggestion;
				// remove the entry so it isnt displayed multiple times
				hashTable.Remove(transposition);

			}
			// deletion
			string deletion = word.substr(0, x)+ word.substr(x + 1);
			if(hashTable.Count(deletion))
			{
				cout<<deletion<<", ";
				remove[numRemove++] = deletion;
				++suggestion;
				// remove the entry so it isnt displayed multiple times
				hashTable.Remove(deletion);
			}
		}		
		// place the removed items back inside the hash table
		while(numRemove>=0)
		{
			hashTable.Insert(remove[numRemove--]);
		}
		if(suggestion < 1)
		{
			cout<<"No spelling suggestion found...";
		}
		cout<<endl<<endl;
	}
	return result;
}// end of SpellCheck

string ToLowerCase(string word)
{
	for(unsigned x = 0; x < word.length(); ++x)
	{
		word[x] = tolower(word[x]);
	}
	return word;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 31, 2013
//    Taken From: http://programmingnotes.org/
//    File:  SpellCheck.cpp
//    Description: This is a simple spell checker which tests the HashTable.h
//          class. 
// ============================================================================
#include <iostream>
#include <fstream>
#include <cctype>
#include <cstring>
#include <string>
#include <iomanip>
#include <ctime>
#include <limits>
#include "HashTable.h"
using namespace std;
 
// iterator declaration for hash table
typedef HashTable<string>::Iterator iterDec;
 
// hash table size
const int TABLE_SIZE = 19000;
 
// strtok delimiters
const char* DELIMITERS = " ,.-\':;?()+*/\\%$#!\"@\^&";
 
// function prototypes
void PrintTableStats(HashTable<string>& hashTable);
int SpellCheck(HashTable<string>& hashTable, string word);
string ToLowerCase(string word);
 
int main()
{	
	// declare variables
	int result = 0;
	string userInput;
	string currWord;
	clock_t beg; // used to time the hashtable load
	clock_t end; // used to time the hashtable load
	char response;
	ifstream infile;
	HashTable<string> hashTable(TABLE_SIZE);
 
	// open the dictionary file
	infile.open("INPUT_Dictionary_programmingnotes_freeweq_com.txt");
 
	// check if the file exists, EXIT if it doesnt
	if(infile.fail())
	{
		cout<<"\n\n**ERROR - The dictionary file could not be found...\n";
		exit(1);
	}
 
	cerr<<"\nLoading dictionary....";		
	beg = clock(); // start the timer
 
	// get data from file and put into hashtable
	while(infile >> currWord)
	{
		// makes sure duplicate words arent inserted into table
		if(!hashTable.Count(currWord))
		{
			hashTable.Insert(currWord);
		}
	}	
	infile.close();
	PrintTableStats(hashTable);	
 
	end = clock()-beg; // end the timer
	cout<<"\n\nDictionary loaded in "<<
		(double)end / ((double)CLOCKS_PER_SEC)<<" secs!";
	
	// creates a line separator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(50)<<""<<endl;	
 
	do{ // get user input
		cout<<"\n>> Please enter a sentence: ";	
		getline(cin,userInput);
		cout<<endl;
 
		// split each word from the string into individual words to check if 
		// they are spelled correctly 
		char* splitInput = strtok(const_cast<char*>(userInput.c_str()),DELIMITERS);
		while(splitInput!=NULL)
		{		
			currWord = splitInput;
			currWord = ToLowerCase(currWord);
			result += SpellCheck(hashTable,currWord);
			splitInput = strtok(NULL,DELIMITERS);
		}
 
		// display results		
		if(result > 0)
		{
			cout<<"Number of words spelled incorrectly: "<<result<<endl;
			result = 0;
		}
 
		// ask for more data
		cout<<"\nDo you want to enter another sentence? (y/n): ";
		cin >> response;
		cin.ignore(numeric_limits<streamsize>::max(),'\n'); // clear the cin buffer
	}while(toupper(response)=='Y');
 
	cout<<"\nBYE!!\n";
 
	return 0;
}// end of main
 
void PrintTableStats(HashTable<string>& hashTable)
{
	int largestBucket = -9999999;
	int largestIndex = 0;
	int smallestBucket = 9999999;
	int smallestIndex = 0;
	double numBuckestUsed = 0;
	ofstream outfile("OUTPUT_HashTable_Stats_programmingnotes_freeweq_com.txt");
	
	for(int x=0; x < hashTable.TableSize(); ++x)
	{
		// iterator is used to traverse each hashtable bucket
		iterDec it = hashTable.begin(x);
		if(!hashTable.IsEmpty(x))
		{
			if(smallestBucket > hashTable.BucketSize(x))
			{
				smallestBucket = hashTable.BucketSize(x);
				smallestIndex = x;
			}
			if(largestBucket < hashTable.BucketSize(x))
			{
				largestBucket = hashTable.BucketSize(x);
				largestIndex = x;
			}
			++numBuckestUsed;
			outfile<<"\nBucket #"<<x<<":\n";
			for(int y = 0; y < hashTable.BucketSize(x); ++y)
			{
				outfile <<"\t"<< it[y] << endl;
			}
		}
	}
	cout<<"Complete!\n";
 
	// creates a line separator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(50)<<""<<endl;
 
	cout<<"Total dictionary words = "<<hashTable.TotalElems()<<endl
		<<"Hash table size = "<<hashTable.TableSize()<<endl
		<<"Largest bucket size = "<<largestBucket<< " items at index #"<<largestIndex<<endl
		<<"Smallest bucket size = "<<smallestBucket<< " items at index #"<<smallestIndex<<endl
		<<"Total buckets used = "<<numBuckestUsed<<endl
		<<"Total percent of hash table used = "<<(numBuckestUsed/hashTable.TableSize())*100<<"%"<<endl
		<<"Average bucket size = "<<(hashTable.TotalElems()/numBuckestUsed)<<" items";
}// end of PrintTableStats
 
int SpellCheck(HashTable<string>& hashTable, string word)
{	
	int result = 0;
	int suggestion = 0;
	string remove[256];
	int numRemove=0;
 
	if(!hashTable.Count(word))
	{
		++result;
		cout<<"** "<<word<<": ";			
		// alteration & insertion
		for(unsigned x = 0; x < word.length(); ++x)
		{		
			string alteration = word;
			for(char c = 'a'; c <= 'z'; ++c)
			{
				//alteration
				alteration[x] = c;
				if(hashTable.Count(alteration))
				{
					cout<<alteration<<", ";
					remove[numRemove++] = alteration;
					++suggestion;
					// remove the entry so it isnt displayed multiple times
					hashTable.Remove(alteration);
				}
				//insertion
				string insertion = word.substr(0, x) + c + word.substr(x);
				if(hashTable.Count(insertion))
				{
					cout<<insertion<<", ";	
					remove[numRemove++] = insertion;
					++suggestion;
					// remove the entry so it isnt displayed multiple times
					hashTable.Remove(insertion);
				}
			}
		}
		// transposition & deletion	
		for(unsigned x = 0; x < word.length()-1;++x) 
		{
			// transposition 
			string transposition = word.substr(0,x) + word[x+1] + word[x] + word.substr(x+2);
			if(hashTable.Count(transposition))
			{
				cout<<transposition<<", ";
				remove[numRemove++] = transposition;
				++suggestion;
				// remove the entry so it isnt displayed multiple times
				hashTable.Remove(transposition);
 
			}
			// deletion
			string deletion = word.substr(0, x)+ word.substr(x + 1);
			if(hashTable.Count(deletion))
			{
				cout<<deletion<<", ";
				remove[numRemove++] = deletion;
				++suggestion;
				// remove the entry so it isnt displayed multiple times
				hashTable.Remove(deletion);
			}
		}		
		// place the removed items back inside the hash table
		while(numRemove>=0)
		{
			hashTable.Insert(remove[numRemove--]);
		}
		if(suggestion < 1)
		{
			cout<<"No spelling suggestion found...";
		}
		cout<<endl<<endl;
	}
	return result;
}// end of SpellCheck
 
string ToLowerCase(string word)
{
	for(unsigned x = 0; x < word.length(); ++x)
	{
		word[x] = tolower(word[x]);
	}
	return word;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Remember to include the data file.

Once compiled, you should get this as your output

Loading dictionary....Complete!
-------------------------------------------------- Total dictionary words = 61286 Hash table size = 19000 Largest bucket size = 13 items at index #1551 Smallest bucket size = 1 items at index #11 Total buckets used = 18217 Total percent of hash table used = 95.8789% Average bucket size = 3.36422 items Dictionary loaded in 1.861 secs! -------------------------------------------------- >> Please enter a sentence: wird ** wird: bird, gird, ward, weird, word, wild, wind, wire, wired, wiry, Number of words spelled incorrectly: 1 Do you want to enter another sentence? (y/n): y -------------------------------------------------- >> Please enter a sentence: woprd ** woprd: word, Number of words spelled incorrectly: 1 Do you want to enter another sentence? (y/n): y -------------------------------------------------- >> Please enter a sentence: wrd ** wrd: ard, ord, ward, wed, word, Number of words spelled incorrectly: 1 Do you want to enter another sentence? (y/n): y -------------------------------------------------- >> Please enter a sentence: wrod ** wrod: brod, trod, wood, rod, word, Number of words spelled incorrectly: 1 Do you want to enter another sentence? (y/n): y -------------------------------------------------- >> Please enter a sentence: New! Safe and efective ** efective: defective, effective, elective, Number of words spelled incorrectly: 1 Do you want to enter another sentence? (y/n): y -------------------------------------------------- >> Please enter a sentence: This is a sentance with no corections gygyuigigigiug ** sentance: sentence, ** corections: corrections, ** gygyuigigigiug: No spelling suggestion found... Number of words spelled incorrectly: 3 Do you want to enter another sentence? (y/n): n
BYE!!

C++ || Custom Template Hash Table With Iterator Using Separate Chaining

January 18, 2013 admin No comments

Looking for sample code for a Hash Map? Click here!

Before we get into the code, what is a Hash Table? Simply put, a Hash Table is a data structure used to implement an associative array; one that can map unique “keys” to specific values. While a standard array requires that indice subscripts be integers, a hash table can use a floating point value, a string, another array, or even a structure as the index. That index is called the “key,” and the contents within the array at that specific index location is called the value. A hash table uses a hash function to generate an index into the table, creating buckets or slots, from which the correct value can be found.

To illustrate, compare a standard array full of data (100 elements). If the position was known for the specific item that we wanted to access within the array, we could quickly access it. For example, if we wanted to access the data located at index #5 in the array, we could access it by doing:

array[5]; // do something with the data

Here, we dont have to search through each element in the array to find what we need, we just access it at index #5. The question is, how do we know that index #5 stores the data that we are looking for? If we have a large set of data, doing a sequential search over each item within the array can be very inefficient. That is where hashing comes in handy. Given a “key,” we can apply a hash function to a unique index or bucket to find the data that we wish to access.

So in essence, a hash table is a data structure that stores key/value pairs, and is typically used because they are ideal for doing a quick search of items.

Though hashing is ideal, it isnt perfect. It is possible for multiple items to be hashed into the same location. Hash “collisions” are practically unavoidable when hashing large data sets. The code demonstrated on this page handles collisions via separate chaining, utilizing an array of linked list head nodes to store multiple values within one bucket – should any collisions occur.

An iterator was also implemented, making data access that much more simple within the hash table class. Click here for an overview demonstrating how custom iterators can be built.

Looking for sample code for a Hash Map? Click here!

=== CUSTOM TEMPLATE HASH TABLE WITH ITERATOR ===





		
		
			#include 'HashTable.h' - Hash Table With Iterator
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 18, 2013
//    Taken From: http://programmingnotes.org/
//    File:  HashTable.h
//    Description: This is a class which implements various functions which
//          demonstrates the use of a Hash Table.
// ============================================================================
#ifndef TEMPLATE_HASH_TABLE
#define TEMPLATE_HASH_TABLE
#include <iostream>
#include <string>
#include <sstream>
#include <cstdlib>

// if user doesnt define, this is the
// default hash table size
const int HASH_SIZE = 100;

template <class ItemType>
class HashTable
{
public:
    HashTable(int hashSze = HASH_SIZE);
        /*   Function: Constructor initializes hash table
            Precondition: None
            Postcondition: Defines private variables */
    bool IsEmpty(int key);
        /*   Function: Determines whether hash table is empty at the given key
            Precondition: Hash table has been created
            Postcondition: The function = true if the hash table is empty and the
                             function = false if hash table is not empty */
    bool  IsFull();
        /*   Function: Determines whether hash table is full
            Precondition: Hash table has been created
            Postcondition: The function = true if the hash table is full and the
                             function = false if hash table is not full */
    int Hash(ItemType newItem);
        /*   Function: Computes and returns a unique hash key for a given item
                        The returned key is the given cell where the item resides
            Precondition:  Hash table has been created and is not full
            Postcondition: The hash key is returned */
    void Insert(ItemType newItem);
        /*   Function: Adds newItem to the back of the list at a given key in the hash table
                         A unique hash key is automatically generated for each newItem
            Precondition:  Hash table has been created and is not full
            Postcondition: Item is in the hash table */
    void Append(int key, ItemType newItem);
        /*   Function: Adds new item to the end of the list at a given
                         key in the hash table
            Precondition:  Hash table has been created and is not full
            Postcondition: Item is in the hash table */
    bool Remove(ItemType deleteItem, int key = -1);
        /*   Function: Removes the first instance from the table whose value is "deleteItem"
                      Optional second parameter indicates the key where deleteItem is located
            Precondition:  Hash table has been created and is not empty
            Postcondition: The function = true if deleteItem is found and the
                             function = false if deleteItem is not found */
    void Sort(int key);
        /*   Function: Sort the items in the table at the given key
            Precondition: Hash table has been initialized
            Postcondition: The hash table is sorted */
    int TableSize();
        /*   Function: Return the size of the hash table
            Precondition: Hash table has been initialized
            Postcondition: The size of the hash table is returned */
    int TotalElems();
        /*   Function: Return the total number of elements contained in the hash table
            Precondition: Hash table has been initialized
            Postcondition: The size of the hash table is returned */
    int BucketSize(int key);
        /*   Function: Return the number of items contained in the hash table
                        cell at the given key
            Precondition: Hash table has been initialized
            Postcondition: The size of the given key cell is returned */
    int Count(ItemType searchItem);
        /*   Function: Return the number of times searchItem appears in the table.
                        Only works on items located in their correctly hashed cells
            Precondition: Hash table has been initialized
            Postcondition: The number of times searchItem appears in the table is returned */
    void MakeEmpty();
        /*   Function: Initializes hash table to an empty state
            Precondition: Hash table has been created
            Postcondition: Hash table no longer exists */
    ~HashTable();
        /*   Function: Removes the hash table
            Precondition: Hash table has been declared
            Postcondition: Hash table no longer exists */

    //  -- ITERATOR CLASS --
    class Iterator;
        /*   Function: Class declaration to the iterator
            Precondition: Hash table has been declared
            Postcondition: Hash Iterator has been declared */

    Iterator begin(int key){return(!IsEmpty(key)) ? head[key]:NULL;}
        /*   Function: Returns the beginning of the current hash cell list
            Precondition: Hash table has been declared
            Postcondition: Hash cell has been returned to the Iterator */

    Iterator end(int key=0){return NULL;}
        /*   Function: Returns the end of the current hash cell list
            Precondition: Hash table has been declared
            Postcondition: Hash cell has been returned to the Iterator */

private:
    struct node
    {
        ItemType currentItem;
        node* next;
    };
    node** head; // array of linked list declaration - front of each hash table cell
    int hashSize; // the size of the hash table (how many cells it has)
    int totElems; // holds the total number of elements in the entire table
    int* bucketSize; // holds the total number of elems in each specific hash table cell
};

//=========================  Implementation  ================================//

template<class ItemType>
HashTable<ItemType>::HashTable(int hashSze)
{
    hashSize = hashSze;
    head = new node*[hashSize];
    bucketSize = new int[hashSize];
    for(int x=0; x < hashSize; ++x)
    {
        head[x] = NULL;
        bucketSize[x] = 0;
    }
    totElems = 0;
}/* End of HashTable */

template<class ItemType>
bool HashTable<ItemType>::IsEmpty(int key)
{
    if(key >=0 && key < hashSize)
    {
        return head[key] == NULL;
    }
    return true;
}/* End of IsEmpty */

template<class ItemType>
bool HashTable<ItemType>::IsFull()
{
    try
    {
        node* location = new node;
        delete location;
        return false;
    }
    catch(std::bad_alloc&)
    {
        return true;
    }
}/* End of IsFull */

template<class ItemType>
int HashTable<ItemType>::Hash(ItemType newItem)
{
    long h = 19937;
    std::stringstream convert;

    // convert the parameter to a string using "stringstream" which is done
    // so we can hash multiple datatypes using only one function
    convert << newItem;
    std::string temp = convert.str();

    for(unsigned x=0; x < temp.length(); ++x)
    {
        h = (h << 6) ^ (h >> 26) ^ temp[x];
    }
    return abs(h % hashSize);
} /* End of Hash */

template<class ItemType>
void HashTable<ItemType>::Insert(ItemType newItem)
{
    if(IsFull())
    {
        //std::cout<<"nINSERT ERROR - HASH TABLE FULLn";
    }
    else
    {
        int key = Hash(newItem);
        Append(key,newItem);
    }
}/* End of Insert */

template<class ItemType>
void HashTable<ItemType>::Append(int key, ItemType newItem)
{
    if(IsFull())
    {
        //std::cout<<"nAPPEND ERROR - HASH TABLE FULLn";
    }
    else
    {
        node* newNode = new node;  // adds new node
        newNode-> currentItem = newItem;
        newNode-> next = NULL;

        if(IsEmpty(key))
        {
            head[key] = newNode;
        }
        else
        {
            node* tempPtr = head[key];
            while(tempPtr-> next != NULL)
            {
                tempPtr = tempPtr-> next;
            }
            tempPtr-> next = newNode;
        }
        ++bucketSize[key];
        ++totElems;
    }
}/* End of Append */

template<class ItemType>
bool HashTable<ItemType>::Remove(ItemType deleteItem, int key)
{
    bool isFound = false;
    node* tempPtr;
    if(key == -1)
    {
        key = Hash(deleteItem);
    }

    if(IsEmpty(key))
    {
        //std::cout<<"nREMOVE ERROR - HASH TABLE EMPTYn";
    }
    else if(head[key]->currentItem == deleteItem)
    {
        tempPtr = head[key];
        head[key] = head[key]-> next;
        delete tempPtr;
        --totElems;
        --bucketSize[key];
        isFound = true;
    }
    else
    {
        for(tempPtr = head[key];tempPtr->next!=NULL;tempPtr=tempPtr->next)
        {
            if(tempPtr->next->currentItem == deleteItem)
            {
                node* deleteNode = tempPtr->next;
                tempPtr-> next = tempPtr-> next-> next;
                delete deleteNode;
                isFound = true;
                --totElems;
                --bucketSize[key];
                break;
            }
        }
    }
    return isFound;
}/* End of Remove */

template<class ItemType>
void HashTable<ItemType>::Sort(int key)
{
    if(IsEmpty(key))
    {
        //std::cout<<"nSORT ERROR - HASH TABLE EMPTYn";
    }
    else
    {
        int listSize = BucketSize(key);
        bool sorted = false;

        do{
            sorted = true;
            int x = 0;
            for(node* tempPtr = head[key];
                tempPtr->next!=NULL && x < listSize-1;
                tempPtr=tempPtr->next,++x)
            {
                if(tempPtr-> currentItem > tempPtr->next->currentItem)
                {
                    ItemType temp = tempPtr-> currentItem;
                    tempPtr-> currentItem = tempPtr->next->currentItem;
                    tempPtr->next->currentItem = temp;
                    sorted = false;
                }
            }
            --listSize;
        }while(!sorted);
    }
}/* End of Sort */

template<class ItemType>
int HashTable<ItemType>::TableSize()
{
    return hashSize;
}/* End of TableSize */

template<class ItemType>
int HashTable<ItemType>::TotalElems()
{
    return totElems;
}/* End of TotalElems */

template<class ItemType>
int HashTable<ItemType>::BucketSize(int key)
{
    return(!IsEmpty(key)) ? bucketSize[key]:0;
}/* End of BucketSize */

template<class ItemType>
int HashTable<ItemType>::Count(ItemType searchItem)
{
    int key = Hash(searchItem);
    int search = 0;

    if(IsEmpty(key))
    {
        //std::cout<<"nCOUNT ERROR - HASH TABLE EMPTYn";
    }
    else
    {
        for(node* tempPtr = head[key];tempPtr!=NULL;tempPtr=tempPtr->next)
        {
            if(tempPtr->currentItem == searchItem)
            {
                ++search;
            }
        }
    }
    return search;
}/* End of Count */

template<class ItemType>
void HashTable<ItemType>::MakeEmpty()
{
    totElems = 0;
    for(int x=0; x < hashSize; ++x)
    {
        if(!IsEmpty(x))
        {
            //std::cout << "Destroying nodes ...n";
            while(!IsEmpty(x))
            {
                node* temp = head[x];
                //std::cout << temp-> currentItem <<std::endl;
                head[x] = head[x]-> next;
                delete temp;
            }
        }
        bucketSize[x] = 0;
    }
}/* End of MakeEmpty */

template<class ItemType>
HashTable<ItemType>::~HashTable()
{
    MakeEmpty();
    delete[] head;
    delete[] bucketSize;
}/* End of ~HashTable */

//   END OF THE HASH TABLE CLASS
// -----------------------------------------------------------
//   START OF THE HASH TABLE ITERATOR CLASS

template <class ItemType>
class HashTable<ItemType>::Iterator :
        public std::iterator<std::forward_iterator_tag,ItemType>,
        public HashTable<ItemType>
    {
public:
    // Iterator constructor
    Iterator(node* otherIter = NULL)
    {
        itHead = otherIter;
    }
    ~Iterator() {}
    // The assignment and relational operators are straightforward
    Iterator& operator=(const Iterator& other)
    {
        itHead = other.itHead;
        return(*this);
    }
    bool operator==(const Iterator& other)const
    {
        return itHead == other.itHead;
    }
    bool operator!=(const Iterator& other)const
    {
        return itHead != other.itHead;
    }
    bool operator<(const Iterator& other)const
    {
        return itHead < other.itHead;
    }
    bool operator>(const Iterator& other)const
    {
        return other.itHead < itHead;
    }
    bool operator<=(const Iterator& other)const
    {
        return (!(other.itHead < itHead));
    }
    bool operator>=(const Iterator& other)const
    {
        return (!(itHead < other.itHead));
    }
    // Update my state such that I refer to the next element in the
    // HashTable.
    Iterator operator+(int incr)
    {
        node* temp = itHead;
        for(int x=0; x < incr && temp!= NULL; ++x)
        {
            temp = temp->next;
        }
        return temp;
    }
    Iterator operator+=(int incr)
    {
        for(int x=0; x < incr && itHead!= NULL; ++x)
        {
            itHead = itHead->next;
        }
        return itHead;
    }
    Iterator& operator++() // pre increment
    {
        if(itHead != NULL)
        {
            itHead = itHead->next;
        }
        return(*this);
    }
    Iterator operator++(int) // post increment
    {
        node* temp = itHead;
        this->operator++();
        return temp;
    }
    ItemType& operator[](int incr)
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL || (*this + incr) == NULL)
        {
            return junk;
        }
        return(*(*this + incr));
    }
    // Return a reference to the value in the node.  I do this instead
    // of returning by value so a caller can update the value in the
    // node directly.
    ItemType& operator*()
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL)
        {
            return junk;
        }
        return itHead->currentItem;
    }
    ItemType* operator->()
    {
        return(&**this);
    }
private:
    node* itHead;
    ItemType junk;
};
#endif // http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 18, 2013
//    Taken From: http://programmingnotes.org/
//    File:  HashTable.h
//    Description: This is a class which implements various functions which
//          demonstrates the use of a Hash Table.
// ============================================================================
#ifndef TEMPLATE_HASH_TABLE
#define TEMPLATE_HASH_TABLE
#include <iostream>
#include <string>
#include <sstream>
#include <cstdlib>
 
// if user doesnt define, this is the
// default hash table size
const int HASH_SIZE = 100;
 
template <class ItemType>
class HashTable
{
public:
    HashTable(int hashSze = HASH_SIZE);
        /*   Function: Constructor initializes hash table
            Precondition: None
            Postcondition: Defines private variables */
    bool IsEmpty(int key);
        /*   Function: Determines whether hash table is empty at the given key
            Precondition: Hash table has been created
            Postcondition: The function = true if the hash table is empty and the
                             function = false if hash table is not empty */
    bool  IsFull();
        /*   Function: Determines whether hash table is full
            Precondition: Hash table has been created
            Postcondition: The function = true if the hash table is full and the
                             function = false if hash table is not full */
    int Hash(ItemType newItem);
        /*   Function: Computes and returns a unique hash key for a given item
                        The returned key is the given cell where the item resides
            Precondition:  Hash table has been created and is not full
            Postcondition: The hash key is returned */
    void Insert(ItemType newItem);
        /*   Function: Adds newItem to the back of the list at a given key in the hash table
                         A unique hash key is automatically generated for each newItem
            Precondition:  Hash table has been created and is not full
            Postcondition: Item is in the hash table */
    void Append(int key, ItemType newItem);
        /*   Function: Adds new item to the end of the list at a given
                         key in the hash table
            Precondition:  Hash table has been created and is not full
            Postcondition: Item is in the hash table */
    bool Remove(ItemType deleteItem, int key = -1);
        /*   Function: Removes the first instance from the table whose value is "deleteItem"
                      Optional second parameter indicates the key where deleteItem is located
            Precondition:  Hash table has been created and is not empty
            Postcondition: The function = true if deleteItem is found and the
                             function = false if deleteItem is not found */
    void Sort(int key);
        /*   Function: Sort the items in the table at the given key
            Precondition: Hash table has been initialized
            Postcondition: The hash table is sorted */
    int TableSize();
        /*   Function: Return the size of the hash table
            Precondition: Hash table has been initialized
            Postcondition: The size of the hash table is returned */
    int TotalElems();
        /*   Function: Return the total number of elements contained in the hash table
            Precondition: Hash table has been initialized
            Postcondition: The size of the hash table is returned */
    int BucketSize(int key);
        /*   Function: Return the number of items contained in the hash table
                        cell at the given key
            Precondition: Hash table has been initialized
            Postcondition: The size of the given key cell is returned */
    int Count(ItemType searchItem);
        /*   Function: Return the number of times searchItem appears in the table.
                        Only works on items located in their correctly hashed cells
            Precondition: Hash table has been initialized
            Postcondition: The number of times searchItem appears in the table is returned */
    void MakeEmpty();
        /*   Function: Initializes hash table to an empty state
            Precondition: Hash table has been created
            Postcondition: Hash table no longer exists */
    ~HashTable();
        /*   Function: Removes the hash table
            Precondition: Hash table has been declared
            Postcondition: Hash table no longer exists */
 
    //  -- ITERATOR CLASS --
    class Iterator;
        /*   Function: Class declaration to the iterator
            Precondition: Hash table has been declared
            Postcondition: Hash Iterator has been declared */
 
    Iterator begin(int key){return(!IsEmpty(key)) ? head[key]:NULL;}
        /*   Function: Returns the beginning of the current hash cell list
            Precondition: Hash table has been declared
            Postcondition: Hash cell has been returned to the Iterator */
 
    Iterator end(int key=0){return NULL;}
        /*   Function: Returns the end of the current hash cell list
            Precondition: Hash table has been declared
            Postcondition: Hash cell has been returned to the Iterator */
 
private:
    struct node
    {
        ItemType currentItem;
        node* next;
    };
    node** head; // array of linked list declaration - front of each hash table cell
    int hashSize; // the size of the hash table (how many cells it has)
    int totElems; // holds the total number of elements in the entire table
    int* bucketSize; // holds the total number of elems in each specific hash table cell
};
 
//=========================  Implementation  ================================//
 
template<class ItemType>
HashTable<ItemType>::HashTable(int hashSze)
{
    hashSize = hashSze;
    head = new node*[hashSize];
    bucketSize = new int[hashSize];
    for(int x=0; x < hashSize; ++x)
    {
        head[x] = NULL;
        bucketSize[x] = 0;
    }
    totElems = 0;
}/* End of HashTable */
 
template<class ItemType>
bool HashTable<ItemType>::IsEmpty(int key)
{
    if(key >=0 && key < hashSize)
    {
        return head[key] == NULL;
    }
    return true;
}/* End of IsEmpty */
 
template<class ItemType>
bool HashTable<ItemType>::IsFull()
{
    try
    {
        node* location = new node;
        delete location;
        return false;
    }
    catch(std::bad_alloc&)
    {
        return true;
    }
}/* End of IsFull */
 
template<class ItemType>
int HashTable<ItemType>::Hash(ItemType newItem)
{
    long h = 19937;
    std::stringstream convert;
 
    // convert the parameter to a string using "stringstream" which is done
    // so we can hash multiple datatypes using only one function
    convert << newItem;
    std::string temp = convert.str();
 
    for(unsigned x=0; x < temp.length(); ++x)
    {
        h = (h << 6) ^ (h >> 26) ^ temp[x];
    }
    return abs(h % hashSize);
} /* End of Hash */
 
template<class ItemType>
void HashTable<ItemType>::Insert(ItemType newItem)
{
    if(IsFull())
    {
        //std::cout<<"nINSERT ERROR - HASH TABLE FULLn";
    }
    else
    {
        int key = Hash(newItem);
        Append(key,newItem);
    }
}/* End of Insert */
 
template<class ItemType>
void HashTable<ItemType>::Append(int key, ItemType newItem)
{
    if(IsFull())
    {
        //std::cout<<"nAPPEND ERROR - HASH TABLE FULLn";
    }
    else
    {
        node* newNode = new node;  // adds new node
        newNode-> currentItem = newItem;
        newNode-> next = NULL;
 
        if(IsEmpty(key))
        {
            head[key] = newNode;
        }
        else
        {
            node* tempPtr = head[key];
            while(tempPtr-> next != NULL)
            {
                tempPtr = tempPtr-> next;
            }
            tempPtr-> next = newNode;
        }
        ++bucketSize[key];
        ++totElems;
    }
}/* End of Append */
 
template<class ItemType>
bool HashTable<ItemType>::Remove(ItemType deleteItem, int key)
{
    bool isFound = false;
    node* tempPtr;
    if(key == -1)
    {
        key = Hash(deleteItem);
    }
 
    if(IsEmpty(key))
    {
        //std::cout<<"nREMOVE ERROR - HASH TABLE EMPTYn";
    }
    else if(head[key]->currentItem == deleteItem)
    {
        tempPtr = head[key];
        head[key] = head[key]-> next;
        delete tempPtr;
        --totElems;
        --bucketSize[key];
        isFound = true;
    }
    else
    {
        for(tempPtr = head[key];tempPtr->next!=NULL;tempPtr=tempPtr->next)
        {
            if(tempPtr->next->currentItem == deleteItem)
            {
                node* deleteNode = tempPtr->next;
                tempPtr-> next = tempPtr-> next-> next;
                delete deleteNode;
                isFound = true;
                --totElems;
                --bucketSize[key];
                break;
            }
        }
    }
    return isFound;
}/* End of Remove */
 
template<class ItemType>
void HashTable<ItemType>::Sort(int key)
{
    if(IsEmpty(key))
    {
        //std::cout<<"nSORT ERROR - HASH TABLE EMPTYn";
    }
    else
    {
        int listSize = BucketSize(key);
        bool sorted = false;
 
        do{
            sorted = true;
            int x = 0;
            for(node* tempPtr = head[key];
                tempPtr->next!=NULL && x < listSize-1;
                tempPtr=tempPtr->next,++x)
            {
                if(tempPtr-> currentItem > tempPtr->next->currentItem)
                {
                    ItemType temp = tempPtr-> currentItem;
                    tempPtr-> currentItem = tempPtr->next->currentItem;
                    tempPtr->next->currentItem = temp;
                    sorted = false;
                }
            }
            --listSize;
        }while(!sorted);
    }
}/* End of Sort */
 
template<class ItemType>
int HashTable<ItemType>::TableSize()
{
    return hashSize;
}/* End of TableSize */
 
template<class ItemType>
int HashTable<ItemType>::TotalElems()
{
    return totElems;
}/* End of TotalElems */
 
template<class ItemType>
int HashTable<ItemType>::BucketSize(int key)
{
    return(!IsEmpty(key)) ? bucketSize[key]:0;
}/* End of BucketSize */
 
template<class ItemType>
int HashTable<ItemType>::Count(ItemType searchItem)
{
    int key = Hash(searchItem);
    int search = 0;
 
    if(IsEmpty(key))
    {
        //std::cout<<"nCOUNT ERROR - HASH TABLE EMPTYn";
    }
    else
    {
        for(node* tempPtr = head[key];tempPtr!=NULL;tempPtr=tempPtr->next)
        {
            if(tempPtr->currentItem == searchItem)
            {
                ++search;
            }
        }
    }
    return search;
}/* End of Count */
 
template<class ItemType>
void HashTable<ItemType>::MakeEmpty()
{
    totElems = 0;
    for(int x=0; x < hashSize; ++x)
    {
        if(!IsEmpty(x))
        {
            //std::cout << "Destroying nodes ...n";
            while(!IsEmpty(x))
            {
                node* temp = head[x];
                //std::cout << temp-> currentItem <<std::endl;
                head[x] = head[x]-> next;
                delete temp;
            }
        }
        bucketSize[x] = 0;
    }
}/* End of MakeEmpty */
 
template<class ItemType>
HashTable<ItemType>::~HashTable()
{
    MakeEmpty();
    delete[] head;
    delete[] bucketSize;
}/* End of ~HashTable */
 
//   END OF THE HASH TABLE CLASS
// -----------------------------------------------------------
//   START OF THE HASH TABLE ITERATOR CLASS
 
template <class ItemType>
class HashTable<ItemType>::Iterator :
        public std::iterator<std::forward_iterator_tag,ItemType>,
        public HashTable<ItemType>
    {
public:
    // Iterator constructor
    Iterator(node* otherIter = NULL)
    {
        itHead = otherIter;
    }
    ~Iterator() {}
    // The assignment and relational operators are straightforward
    Iterator& operator=(const Iterator& other)
    {
        itHead = other.itHead;
        return(*this);
    }
    bool operator==(const Iterator& other)const
    {
        return itHead == other.itHead;
    }
    bool operator!=(const Iterator& other)const
    {
        return itHead != other.itHead;
    }
    bool operator<(const Iterator& other)const
    {
        return itHead < other.itHead;
    }
    bool operator>(const Iterator& other)const
    {
        return other.itHead < itHead;
    }
    bool operator<=(const Iterator& other)const
    {
        return (!(other.itHead < itHead));
    }
    bool operator>=(const Iterator& other)const
    {
        return (!(itHead < other.itHead));
    }
    // Update my state such that I refer to the next element in the
    // HashTable.
    Iterator operator+(int incr)
    {
        node* temp = itHead;
        for(int x=0; x < incr && temp!= NULL; ++x)
        {
            temp = temp->next;
        }
        return temp;
    }
    Iterator operator+=(int incr)
    {
        for(int x=0; x < incr && itHead!= NULL; ++x)
        {
            itHead = itHead->next;
        }
        return itHead;
    }
    Iterator& operator++() // pre increment
    {
        if(itHead != NULL)
        {
            itHead = itHead->next;
        }
        return(*this);
    }
    Iterator operator++(int) // post increment
    {
        node* temp = itHead;
        this->operator++();
        return temp;
    }
    ItemType& operator[](int incr)
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL || (*this + incr) == NULL)
        {
            return junk;
        }
        return(*(*this + incr));
    }
    // Return a reference to the value in the node.  I do this instead
    // of returning by value so a caller can update the value in the
    // node directly.
    ItemType& operator*()
    {
        // Return "junk" data
        // to prevent the program from crashing
        if(itHead == NULL)
        {
            return junk;
        }
        return itHead->currentItem;
    }
    ItemType* operator->()
    {
        return(&**this);
    }
private:
    node* itHead;
    ItemType junk;
};
#endif // http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The iterator class starts on line #368, and is built to support most of the standard relational operators, as well as arithmetic operators such as ‘+,+=,++’ (pre/post increment). The * (star), bracket [] and -> arrow operators are also supported. Click here for an overview demonstrating how custom iterators can be built.

The rest of the code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Looking for sample code for a Hash Map? Click here!

===== DEMONSTRATION HOW TO USE =====

Use of the above template class is the same as many of its STL template class counterparts. Here are sample programs demonstrating its use.





		
		
			#1 - Demonstrate Basic Use
			
C++
			
			// DEMONSTRATE USE OF THE REMOVE AND SORT FUNCTIONS
#include <iostream>
#include <ctime>
#include <string>
#include <cstdlib>
#include <iomanip>
#include "HashTable.h"
using namespace std;

// iterator declarations
typedef HashTable<string>::Iterator strIterDec;

// hash table size
const int TABLE_SIZE = 5;

int main()
{
	// delcare variables
	srand(time(NULL));
	const string names[]={"Alva","Edda","Hiram","Lemuel","Della","Roseann","Sang",
        "Evelia","Claire","Marylou","Magda","Irvin","Reagan","Deb","Hillary",
        "Tuyetm","Cherilyn","Amina","Justin","Neville","Jessica","Demi",
        "Graham","Cinderella","Freddy","Vivan","Marjorie","Krystal","Liza",
        "Spencer","Jordon","Bernie","Geraldine","Kati","Jetta","Carmella",
        "Chery","Earlene","Gene","Lorri","Albertina","Ula","Karena","Johanna",
        "Alex","Tobias","Lashawna","Domitila","Chantel","Deneen","Nigel",
        "Lashanda","Donn","Theda","Many","Jeramy","Jodee","Tamra","Dessie",
        "Lawrence","Jaime","Basil","Roger","Cythia","Homer","Lilliam","Victoria",
        "Tod","Harley","Meghann","Jacquelyne","Arie","Rosemarie","Lyndon","Blanch",
        "Kenneth","Perkins","Kaleena"};

	int nameLen = sizeof(names)/sizeof(names[0]); 

	// Hash table class declarations
	HashTable<string> strHash(TABLE_SIZE);

	// insert 10 items into each hash table
	for(int x=0; x < (TABLE_SIZE*2); ++x)
	{
		// place all data in bucket 0
		// NOTE: you dont want to place all data into one
		// bucket, this is done for demo purposes only
		// Normally use the "Insert" function instead
		strHash.Append(0,names[rand()%(nameLen-1)]);
	}

	// assign the iterator to bucket 0
	strIterDec it = strHash.begin(0);

	// display bucket size
	cout<<"Bucket #0 has "<<strHash.BucketSize(0)<<" items"<<endl;

	// display the first item
	cout<<"The first element in bucket #0 is "<< it[0] <<endl;	

	// remove the first item in bucket 0
	// NOTE: the second parameter is optional
	// but since we know we want bucket 0, we use it here
	strHash.Remove(it[0],0);

	// update the iterator to the new table state
	it = strHash.begin(0);

	// display the new first item	
	cout<<"nNow bucket #0 has "<<strHash.BucketSize(0)<<" items"<<endl;
	cout<<"The first element in bucket #0 is "<< it[0] <<endl;

	// display all the items within the "strHash" table
	cout<<"nThe unsorted items in strHash bucket #0:n";
	for(int x=0; x < strHash.BucketSize(0); ++x)
	{		
		cout << "it[] = " << it[x] << endl;
	}

	// sort the items in bucket 0
	strHash.Sort(0);

	// display all the items within the "strHash" table
	cout<<"nThe sorted items in strHash bucket #0:n";
	for(int x=0; x < strHash.BucketSize(0); ++x)
	{		
		cout << "it[] = " << it[x] << endl;
	}

	return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// DEMONSTRATE USE OF THE REMOVE AND SORT FUNCTIONS
#include <iostream>
#include <ctime>
#include <string>
#include <cstdlib>
#include <iomanip>
#include "HashTable.h"
using namespace std;
 
// iterator declarations
typedef HashTable<string>::Iterator strIterDec;
 
// hash table size
const int TABLE_SIZE = 5;
 
int main()
{
	// delcare variables
	srand(time(NULL));
	const string names[]={"Alva","Edda","Hiram","Lemuel","Della","Roseann","Sang",
        "Evelia","Claire","Marylou","Magda","Irvin","Reagan","Deb","Hillary",
        "Tuyetm","Cherilyn","Amina","Justin","Neville","Jessica","Demi",
        "Graham","Cinderella","Freddy","Vivan","Marjorie","Krystal","Liza",
        "Spencer","Jordon","Bernie","Geraldine","Kati","Jetta","Carmella",
        "Chery","Earlene","Gene","Lorri","Albertina","Ula","Karena","Johanna",
        "Alex","Tobias","Lashawna","Domitila","Chantel","Deneen","Nigel",
        "Lashanda","Donn","Theda","Many","Jeramy","Jodee","Tamra","Dessie",
        "Lawrence","Jaime","Basil","Roger","Cythia","Homer","Lilliam","Victoria",
        "Tod","Harley","Meghann","Jacquelyne","Arie","Rosemarie","Lyndon","Blanch",
        "Kenneth","Perkins","Kaleena"};
 
	int nameLen = sizeof(names)/sizeof(names[0]); 
 
	// Hash table class declarations
	HashTable<string> strHash(TABLE_SIZE);
 
	// insert 10 items into each hash table
	for(int x=0; x < (TABLE_SIZE*2); ++x)
	{
		// place all data in bucket 0
		// NOTE: you dont want to place all data into one
		// bucket, this is done for demo purposes only
		// Normally use the "Insert" function instead
		strHash.Append(0,names[rand()%(nameLen-1)]);
	}
 
	// assign the iterator to bucket 0
	strIterDec it = strHash.begin(0);
 
	// display bucket size
	cout<<"Bucket #0 has "<<strHash.BucketSize(0)<<" items"<<endl;
 
	// display the first item
	cout<<"The first element in bucket #0 is "<< it[0] <<endl;	
 
	// remove the first item in bucket 0
	// NOTE: the second parameter is optional
	// but since we know we want bucket 0, we use it here
	strHash.Remove(it[0],0);
 
	// update the iterator to the new table state
	it = strHash.begin(0);
 
	// display the new first item	
	cout<<"nNow bucket #0 has "<<strHash.BucketSize(0)<<" items"<<endl;
	cout<<"The first element in bucket #0 is "<< it[0] <<endl;
 
	// display all the items within the "strHash" table
	cout<<"nThe unsorted items in strHash bucket #0:n";
	for(int x=0; x < strHash.BucketSize(0); ++x)
	{		
		cout << "it[] = " << it[x] << endl;
	}
 
	// sort the items in bucket 0
	strHash.Sort(0);
 
	// display all the items within the "strHash" table
	cout<<"nThe sorted items in strHash bucket #0:n";
	for(int x=0; x < strHash.BucketSize(0); ++x)
	{		
		cout << "it[] = " << it[x] << endl;
	}
 
	return 0;
}// http://programmingnotes.org/

SAMPLE OUTPUT:

Bucket #0 has 10 items The first element in bucket #0 is Homer
Now bucket #0 has 9 items The first element in bucket #0 is Tamra The unsorted items in strHash bucket #0: it[] = Tamra it[] = Lyndon it[] = Johanna it[] = Perkins it[] = Alva it[] = Jordon it[] = Neville it[] = Lawrence it[] = Jetta
The sorted items in strHash bucket #0: it[] = Alva it[] = Jetta it[] = Johanna it[] = Jordon it[] = Lawrence it[] = Lyndon it[] = Neville it[] = Perkins it[] = Tamra





		
		
			#2 - Display Items
			
C++
			
			// DISPLAY ALL DATA INSIDE TABLE USING STD::STRING / INT / STRUCT
#include <iostream>
#include <ctime>
#include <string>
#include <cstdlib>
#include <iomanip>
#include "HashTable.h"
using namespace std;

// sample struct demo
struct MyStruct
{
	string name;
};

// iterator declarations
typedef HashTable<string>::Iterator strIterDec;
typedef HashTable<int>::Iterator intIterDec;
typedef HashTable<MyStruct>::Iterator strctIterDec;

// hash table size
const int TABLE_SIZE = 10;

int main()
{
	// delcare variables
	srand(time(NULL));
	const string names[]={"Alva","Edda","Hiram","Lemuel","Della","Roseann","Sang",
        "Evelia","Claire","Marylou","Magda","Irvin","Reagan","Deb","Hillary",
        "Tuyetm","Cherilyn","Amina","Justin","Neville","Jessica","Demi",
        "Graham","Cinderella","Freddy","Vivan","Marjorie","Krystal","Liza",
        "Spencer","Jordon","Bernie","Geraldine","Kati","Jetta","Carmella",
        "Chery","Earlene","Gene","Lorri","Albertina","Ula","Karena","Johanna",
        "Alex","Tobias","Lashawna","Domitila","Chantel","Deneen","Nigel",
        "Lashanda","Donn","Theda","Many","Jeramy","Jodee","Tamra","Dessie",
        "Lawrence","Jaime","Basil","Roger","Cythia","Homer","Lilliam","Victoria",
        "Tod","Harley","Meghann","Jacquelyne","Arie","Rosemarie","Lyndon","Blanch",
        "Kenneth","Perkins","Kaleena"};
     
	int nameLen = sizeof(names)/sizeof(names[0]); 

	// Hash table class declarations
	HashTable<string> strHash(TABLE_SIZE);
	HashTable<int> intHash = TABLE_SIZE; 
	HashTable<MyStruct> strctHash = TABLE_SIZE;

	// access struct element
	MyStruct strctAccess;	

	// insert 20 items into each hash table
	for(int x=0; x < (TABLE_SIZE*2); ++x)
	{
		// Use the "insert" function to place data into the hash table
		// this function automatically hashes the basic datatypes
		// i.e: int, double, char, char*, string
		strHash.Insert(names[rand()%(nameLen-1)]);
		intHash.Insert(rand()%10000);

		// The "insert" function cant be used on a struct, so we
		// use the "append" function for the struct declaration.
		// We use the "strHash" class declaration to use its
		// hash function, then place the struct in an appropriate 
		// hashed bucket
		strctAccess.name = names[rand()%(nameLen-1)];
		int strctHashKey = strHash.Hash(strctAccess.name);		
		strctHash.Append(strctHashKey,strctAccess);
	}

	// display all the items within the "strHash" table
	for(int x=0; x < strHash.TableSize(); ++x)
	{
		if(!strHash.IsEmpty(x))
		{
			cout<<"nstrHash Bucket #"<<x<<":n";
			for(strIterDec it = strHash.begin(x); it != strHash.end(x); it+=1) 
			{
				// access elements using the * (star) operator
				cout << "*it = " << *it << endl;
			}
		}
	}
	// creates a line seperator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(80)<<""<<endl;

	// display all the items within the "intHash" table
	for(int x=0; x < intHash.TableSize(); ++x)
	{		
		intIterDec it = intHash.begin(x);
		if(!intHash.IsEmpty(x))
		{
			cout<<"nintHash Bucket #"<<x<<":n";
			for(int y = 0; y < intHash.BucketSize(x); ++y) 
			{
				// access elements using the [] operator
				cout << "it[] = " << it[y] << endl;
			}
		}
	}

	// creates a line seperator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(80)<<""<<endl;

	// display all the items within the "strctHash" table
	for(int x=0; x < strctHash.TableSize(); ++x)
	{				
		if(!strctHash.IsEmpty(x))
		{
			cout<<"nstrctHash Bucket #"<<x<<":n";
			for(strctIterDec it = strctHash.begin(x); it!=strctHash.end(x); it=it+1) 
			{
				// access struct/class elements using the -> operator
				cout << "it-> = " << it->name << endl;
			}
		}
	}

	return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// DISPLAY ALL DATA INSIDE TABLE USING STD::STRING / INT / STRUCT
#include <iostream>
#include <ctime>
#include <string>
#include <cstdlib>
#include <iomanip>
#include "HashTable.h"
using namespace std;
 
// sample struct demo
struct MyStruct
{
	string name;
};
 
// iterator declarations
typedef HashTable<string>::Iterator strIterDec;
typedef HashTable<int>::Iterator intIterDec;
typedef HashTable<MyStruct>::Iterator strctIterDec;
 
// hash table size
const int TABLE_SIZE = 10;
 
int main()
{
	// delcare variables
	srand(time(NULL));
	const string names[]={"Alva","Edda","Hiram","Lemuel","Della","Roseann","Sang",
        "Evelia","Claire","Marylou","Magda","Irvin","Reagan","Deb","Hillary",
        "Tuyetm","Cherilyn","Amina","Justin","Neville","Jessica","Demi",
        "Graham","Cinderella","Freddy","Vivan","Marjorie","Krystal","Liza",
        "Spencer","Jordon","Bernie","Geraldine","Kati","Jetta","Carmella",
        "Chery","Earlene","Gene","Lorri","Albertina","Ula","Karena","Johanna",
        "Alex","Tobias","Lashawna","Domitila","Chantel","Deneen","Nigel",
        "Lashanda","Donn","Theda","Many","Jeramy","Jodee","Tamra","Dessie",
        "Lawrence","Jaime","Basil","Roger","Cythia","Homer","Lilliam","Victoria",
        "Tod","Harley","Meghann","Jacquelyne","Arie","Rosemarie","Lyndon","Blanch",
        "Kenneth","Perkins","Kaleena"};
     
	int nameLen = sizeof(names)/sizeof(names[0]); 
 
	// Hash table class declarations
	HashTable<string> strHash(TABLE_SIZE);
	HashTable<int> intHash = TABLE_SIZE; 
	HashTable<MyStruct> strctHash = TABLE_SIZE;
 
	// access struct element
	MyStruct strctAccess;	
 
	// insert 20 items into each hash table
	for(int x=0; x < (TABLE_SIZE*2); ++x)
	{
		// Use the "insert" function to place data into the hash table
		// this function automatically hashes the basic datatypes
		// i.e: int, double, char, char*, string
		strHash.Insert(names[rand()%(nameLen-1)]);
		intHash.Insert(rand()%10000);
 
		// The "insert" function cant be used on a struct, so we
		// use the "append" function for the struct declaration.
		// We use the "strHash" class declaration to use its
		// hash function, then place the struct in an appropriate 
		// hashed bucket
		strctAccess.name = names[rand()%(nameLen-1)];
		int strctHashKey = strHash.Hash(strctAccess.name);		
		strctHash.Append(strctHashKey,strctAccess);
	}
 
	// display all the items within the "strHash" table
	for(int x=0; x < strHash.TableSize(); ++x)
	{
		if(!strHash.IsEmpty(x))
		{
			cout<<"nstrHash Bucket #"<<x<<":n";
			for(strIterDec it = strHash.begin(x); it != strHash.end(x); it+=1) 
			{
				// access elements using the * (star) operator
				cout << "*it = " << *it << endl;
			}
		}
	}
	// creates a line seperator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(80)<<""<<endl;
 
	// display all the items within the "intHash" table
	for(int x=0; x < intHash.TableSize(); ++x)
	{		
		intIterDec it = intHash.begin(x);
		if(!intHash.IsEmpty(x))
		{
			cout<<"nintHash Bucket #"<<x<<":n";
			for(int y = 0; y < intHash.BucketSize(x); ++y) 
			{
				// access elements using the [] operator
				cout << "it[] = " << it[y] << endl;
			}
		}
	}
 
	// creates a line seperator
	cout<<endl;
	cout.fill('-');
	cout<<left<<setw(80)<<""<<endl;
 
	// display all the items within the "strctHash" table
	for(int x=0; x < strctHash.TableSize(); ++x)
	{				
		if(!strctHash.IsEmpty(x))
		{
			cout<<"nstrctHash Bucket #"<<x<<":n";
			for(strctIterDec it = strctHash.begin(x); it!=strctHash.end(x); it=it+1) 
			{
				// access struct/class elements using the -> operator
				cout << "it-> = " << it->name << endl;
			}
		}
	}
 
	return 0;
}// http://programmingnotes.org/

SAMPLE OUTPUT:

strHash Bucket #0: *it = Cinderella *it = Perkins *it = Krystal *it = Roger *it = Roger
strHash Bucket #1: *it = Lilliam *it = Lilliam *it = Theda strHash Bucket #2: *it = Arie strHash Bucket #3: *it = Magda strHash Bucket #6: *it = Edda *it = Irvin *it = Kati *it = Lyndon strHash Bucket #7: *it = Deb *it = Jaime strHash Bucket #8: *it = Neville *it = Victoria strHash Bucket #9: *it = Chery *it = Evelia -------------------------------------------- intHash Bucket #0: it[] = 2449 it[] = 6135 intHash Bucket #1: it[] = 1120 it[] = 852 intHash Bucket #2: it[] = 5727 intHash Bucket #3: it[] = 1174 intHash Bucket #4: it[] = 2775 it[] = 3525 it[] = 8375 intHash Bucket #5: it[] = 4322 it[] = 8722 it[] = 5016 intHash Bucket #6: it[] = 5053 it[] = 7231 it[] = 1571 intHash Bucket #7: it[] = 1666 it[] = 4510 it[] = 1548 it[] = 3646 intHash Bucket #9: it[] = 2756 -------------------------------------------- strctHash Bucket #0: it-> = Cherilyn it-> = Roger strctHash Bucket #1: it-> = Tamra it-> = Alex it-> = Theda strctHash Bucket #2: it-> = Nigel it-> = Alva it-> = Arie strctHash Bucket #4: it-> = Basil strctHash Bucket #5: it-> = Tod strctHash Bucket #6: it-> = Irvin it-> = Lyndon strctHash Bucket #7: it-> = Amina it-> = Hillary it-> = Kenneth it-> = Amina strctHash Bucket #8: it-> = Gene it-> = Lemuel it-> = Gene
strctHash Bucket #9: it-> = Albertina

Java || Snippet – How To Find The Highest & Lowest Numbers Contained In An Integer Array

November 20, 2012 admin No comments

This page will consist of a simple demonstration for finding the highest and lowest numbers contained in an integer array.

REQUIRED KNOWLEDGE FOR THIS SNIPPET

Integer Arrays For Loops Custom Setw/Setfill In Java

Finding the highest/lowest values in an array can be found in one or two ways. The first way would be via a sort, which would obviously render the highest/lowest numbers contained in the array because the values would be sorted in order from highest to lowest. But a sort may not always be practical, especially when you want to keep the array values in the same order that they originally came in.

The second method of finding the highest/lowest values is by traversing through the array, literally checking each value it contains one by one to determine if the current number which is being compared truly is a target value or not. That method will be displayed below.





		
		
			Find The Highest/Lowest Numbers In An Array
			
Java
			
			import java.util.Random;

public class HighestLowestArray
{
	// global variable declaration
	final static int ARRAY_SIZE = 14; // const int allocating space for the array
	static Random rand = new Random(); // this is the call to the "Random" class
	
	public static void main(String[] args)
	{
		// declare & initialize variables
		int[] arry = new int[ARRAY_SIZE];
		int highestScore = -999999;
		int lowestScore = 999999;
	     
		System.out.println("Welcome to My Programming Notes' Java Program.n");
		
		// place random numbers into the array
		for(int x = 0; x < ARRAY_SIZE; ++x)
		{
			arry[x] = rand.nextInt(100)+1;
		} 
		
		System.out.println("Original array values:");
		// Output the original array values
		for(int x = 0; x < ARRAY_SIZE; ++x)
		{
			System.out.print(arry[x]+"  ");
		}
		System.out.println("");
		
		// creates a line seperator
		setwLF("",60,'-');
		
		// use a for loop to go thru the array checking to see the highest/lowest element
		System.out.print("nThese are the highest and lowest array values: ");
		for(int index=0; index < ARRAY_SIZE; ++index)
		{
			// if current score in the array is bigger than the current 'highestScore'
			// element, then set 'highestScore' equal to the current array element
			if(arry[index] > highestScore)
			{
				highestScore = arry[index];
			}
			// if current 'lowestScore' element is bigger than the current array element,
			//  then set 'lowestScore' equal to the current array element
			if(arry[index] < lowestScore)
			{
				lowestScore = arry[index];
			}
		}// end for loop
		
		// display the results to the user
		System.out.print("nHighest: "+highestScore);
		System.out.print("nLowest: "+lowestScore);
		System.out.println("");		
	}// end of main	
	
	static public void setwLF(String str, int width, char fill)
	{		
		for (int x = str.length(); x < width; ++x) 
		{
			System.out.print(fill);	
		}
		System.out.print(str);
	}// end of setwLF	
}// http://programmingnotes.org/
			
				
					
				
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						import java.util.Random;
 
public class HighestLowestArray
{
	// global variable declaration
	final static int ARRAY_SIZE = 14; // const int allocating space for the array
	static Random rand = new Random(); // this is the call to the "Random" class
	
	public static void main(String[] args)
	{
		// declare & initialize variables
		int[] arry = new int[ARRAY_SIZE];
		int highestScore = -999999;
		int lowestScore = 999999;
	     
		System.out.println("Welcome to My Programming Notes' Java Program.n");
		
		// place random numbers into the array
		for(int x = 0; x < ARRAY_SIZE; ++x)
		{
			arry[x] = rand.nextInt(100)+1;
		} 
		
		System.out.println("Original array values:");
		// Output the original array values
		for(int x = 0; x < ARRAY_SIZE; ++x)
		{
			System.out.print(arry[x]+"  ");
		}
		System.out.println("");
		
		// creates a line seperator
		setwLF("",60,'-');
		
		// use a for loop to go thru the array checking to see the highest/lowest element
		System.out.print("nThese are the highest and lowest array values: ");
		for(int index=0; index < ARRAY_SIZE; ++index)
		{
			// if current score in the array is bigger than the current 'highestScore'
			// element, then set 'highestScore' equal to the current array element
			if(arry[index] > highestScore)
			{
				highestScore = arry[index];
			}
			// if current 'lowestScore' element is bigger than the current array element,
			//  then set 'lowestScore' equal to the current array element
			if(arry[index] < lowestScore)
			{
				lowestScore = arry[index];
			}
		}// end for loop
		
		// display the results to the user
		System.out.print("nHighest: "+highestScore);
		System.out.print("nLowest: "+lowestScore);
		System.out.println("");		
	}// end of main	
	
	static public void setwLF(String str, int width, char fill)
	{		
		for (int x = str.length(); x < width; ++x) 
		{
			System.out.print(fill);	
		}
		System.out.print(str);
	}// end of setwLF	
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

Welcome to My Programming Notes' Java Program.
Original array values: 36 35 46 86 86 58 44 38 79 52 27 78 65 79 ------------------------------------------------------------ These are the highest and lowest array values: Highest: 86 Lowest: 27

Java || Modulus – Celsius To Fahrenheit Conversion Displaying Degrees Divisible By 10 Using Modulus

November 20, 2012 admin No comments

This page will consist of two simple programs which demonstrate the use of the modulus operator (%).

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Modulus Do/While Loop Methods (A.K.A "Functions") - What Are They? Simple Math - Divisibility Celsius to Fahrenheit Conversion

===== FINDING THE DIVISIBILITY OF A NUMBER =====

Take a simple arithmetic problem: what’s left over when you divide an odd number by an even number? The answer may not be easy to compute, but we know that it will most likely result in an answer which has a decimal remainder. How would we determine the divisibility of a number in a programming language like Java? That’s where the modulus operator comes in handy.

To have divisibility means that when you divide the first number by another number, the quotient (answer) is a whole number (i.e – no decimal values). Unlike the division operator, the modulus operator (‘%’), has the ability to give us the remainder of a given mathematical operation that results from performing integer division.

To illustrate this, here is a simple program which prompts the user to enter a number. Once the user enters a number, they are asked to enter in a divisor for the previous number. Using modulus, the program will determine if the second number is divisible by the first number. If the modulus result returns 0, the two numbers are divisible. If the modulus result does not return 0, the two numbers are not divisible. The program will keep re-prompting the user to enter in a correct choice until a correct result is obtained.





		
		
			Is It Divisible?
			
Java
			
			import java.util.Scanner;

public class Modulus
{
	// global variable declaration
	static Scanner cin = new Scanner(System.in);
	
	public static void main(String[] args)
	{
		// declare & initialize variables
		int numerator = 0;
		int denominator = 0;
		double multiple = 0;
		
		System.out.println("Welcome to My Programming Notes' Java Program.n");
		
		// get first number
		System.out.print("Please enter a value: ");
		numerator = cin.nextInt();

		// get second number
		System.out.print("nPlease enter a factor of "+numerator+": ");						

		do{ // loop will keep going until the user enters a correct answer
			
			denominator = cin.nextInt();		

			// this is the modulus declaration, which will find the 
			// remainder between the 2 numbers
			multiple = numerator % denominator;	
			
			// if the modulus result returns 0, the 2 numbers
			// are divisible
			if(multiple == 0)
			{
				System.out.println("nCorrect! "+numerator+" is divisible by "
						+denominator);
				System.out.println("n("+numerator+"/"+denominator+") = " +
						""+(numerator/denominator));
			}
			// if the user entered an incorrect choice, promt an error message
			else
			{
				System.out.print("nIncorrect, "+numerator+" is not divisible by "
					+denominator);
				System.out.print(".nnPlease enter a new multiple integer for "
						+numerator+": ");				
			}
		}while(multiple != 0);
		// ^ loop stops once user enters correct choice						
	}// end of main	
}// http://programmingnotes.org/
			
				
					
				
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						import java.util.Scanner;
 
public class Modulus
{
	// global variable declaration
	static Scanner cin = new Scanner(System.in);
	
	public static void main(String[] args)
	{
		// declare & initialize variables
		int numerator = 0;
		int denominator = 0;
		double multiple = 0;
		
		System.out.println("Welcome to My Programming Notes' Java Program.n");
		
		// get first number
		System.out.print("Please enter a value: ");
		numerator = cin.nextInt();
 
		// get second number
		System.out.print("nPlease enter a factor of "+numerator+": ");						
 
		do{ // loop will keep going until the user enters a correct answer
			
			denominator = cin.nextInt();		
 
			// this is the modulus declaration, which will find the 
			// remainder between the 2 numbers
			multiple = numerator % denominator;	
			
			// if the modulus result returns 0, the 2 numbers
			// are divisible
			if(multiple == 0)
			{
				System.out.println("nCorrect! "+numerator+" is divisible by "
						+denominator);
				System.out.println("n("+numerator+"/"+denominator+") = " +
						""+(numerator/denominator));
			}
			// if the user entered an incorrect choice, promt an error message
			else
			{
				System.out.print("nIncorrect, "+numerator+" is not divisible by "
					+denominator);
				System.out.print(".nnPlease enter a new multiple integer for "
						+numerator+": ");				
			}
		}while(multiple != 0);
		// ^ loop stops once user enters correct choice						
	}// end of main	
}// http://programmingnotes.org/

The above program determines if number ‘A’ is divisible be number ‘B’ via modulus. Unlike the division operator, which does not return the remainder of a number, the modulus operator does, thus we are able to find divisibility between two numbers.

To demonstrate the above code, here is a sample run:

Welcome to My Programming Notes' Java Program.
Please enter a value: 21 Please enter a factor of 21: 5 Incorrect, 21 is not divisible by 5. Please enter a new multiple integer for 21: 7 Correct! 21 is divisible by 7
(21/7) = 3

===== CELSIUS TO FAHRENHEIT CONVERSION DISPLAYING DEGREES DIVISIBLE BY 10 =====

Now that we understand how modulus works, the second program shouldn’t be too difficult. This function first prompts the user to enter in an initial (low) value. After the program obtains the low value from the user, the program will ask for another (high) value. After it obtains the needed information, it displays all the degrees, from the range of the low number to the high number, which are divisible by 10. So if the user enters a low value of 3 and a high value of 303, the program will display all of the Celsius to Fahrenheit degrees within that range which are divisible by 10.





		
		
			Celsius To Fahrenheit Conversion
			
Java
			
			import java.util.Scanner;

public class Temperature
{
	// global variable declaration
	static Scanner cin = new Scanner(System.in);
	
	public static void main(String[] args)
	{
		// declare & initialize variables
		int low = 0;
		int high = 0;
		double degreeFahrenhiet = 0;
		double multiple = 0;
		
		System.out.println("Welcome to My Programming Notes' Java Program.n");	
		
		// get data from user
		System.out.print("Enter a low number: ");
		low = cin.nextInt();

		System.out.print("nEnter a high number: ");
		high = cin.nextInt();
		
		// displays data back to user in table form
		System.out.print("nCelsius Fahrenheit:n");
		
		// display the initial 'low' converted degrees to the user
		System.out.println(low+"t"+ConvertCelsiusToFahrenheit(low));	
		
		// this loop displays all the degrees that are divisible by 10
		do{ 
			// this increments the current degree number by 1
			++low;
			
			// this converts the current number from celsius to fahrenhiet
			degreeFahrenhiet = ConvertCelsiusToFahrenheit(low);

			// this is the modulus operation which finds the 
			// numbers which are divisible by 10
			multiple = low % 10;		

			// the program will only display the degrees to the user via
			// cout which are divisible by 10
			if(multiple == 0)
			{
				System.out.println(low+"t"+degreeFahrenhiet);
			}			
		}while(low < high);
		// ^ loop stops once the 'low' variable reaches the 'high' variable	
		
		// displays the 'high' converted degrees to the user
		System.out.println(high+"t"+ConvertCelsiusToFahrenheit(high));		
	}// end of main	
	
	static double ConvertCelsiusToFahrenheit(int degree)
	{
		return ((1.8 * degree) + 32.0);
	}// end of ConvertCelsiusToFahrenheit
}// http://programmingnotes.org/
			
				
					
				
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						import java.util.Scanner;
 
public class Temperature
{
	// global variable declaration
	static Scanner cin = new Scanner(System.in);
	
	public static void main(String[] args)
	{
		// declare & initialize variables
		int low = 0;
		int high = 0;
		double degreeFahrenhiet = 0;
		double multiple = 0;
		
		System.out.println("Welcome to My Programming Notes' Java Program.n");	
		
		// get data from user
		System.out.print("Enter a low number: ");
		low = cin.nextInt();
 
		System.out.print("nEnter a high number: ");
		high = cin.nextInt();
		
		// displays data back to user in table form
		System.out.print("nCelsius Fahrenheit:n");
		
		// display the initial 'low' converted degrees to the user
		System.out.println(low+"t"+ConvertCelsiusToFahrenheit(low));	
		
		// this loop displays all the degrees that are divisible by 10
		do{ 
			// this increments the current degree number by 1
			++low;
			
			// this converts the current number from celsius to fahrenhiet
			degreeFahrenhiet = ConvertCelsiusToFahrenheit(low);
 
			// this is the modulus operation which finds the 
			// numbers which are divisible by 10
			multiple = low % 10;		
 
			// the program will only display the degrees to the user via
			// cout which are divisible by 10
			if(multiple == 0)
			{
				System.out.println(low+"t"+degreeFahrenhiet);
			}			
		}while(low < high);
		// ^ loop stops once the 'low' variable reaches the 'high' variable	
		
		// displays the 'high' converted degrees to the user
		System.out.println(high+"t"+ConvertCelsiusToFahrenheit(high));		
	}// end of main	
	
	static double ConvertCelsiusToFahrenheit(int degree)
	{
		return ((1.8 * degree) + 32.0);
	}// end of ConvertCelsiusToFahrenheit
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

Welcome to My Programming Notes' Java Program.
Enter a low number: 3 Enter a high number: 303
Celsius Fahrenheit: 3..........37.4 10.........50 20.........68 30.........86 40........104 50........122 60........140 70........158 80........176 90........194 100.......212 110.......230 120.......248 130.......266 140.......284 150.......302 160.......320 170.......338 180.......356 190.......374 200.......392 210.......410 220.......428 230.......446 240.......464 250.......482 260.......500 270.......518 280.......536 290.......554 300.......572 303.......577.4

Java || Random Number Guessing Game Using Random & Do/While Loop

November 19, 2012 admin No comments

This is a simple guessing game, which demonstrates the use of the “Random” class to generate random numbers. This program first prompts the user to enter a number between 1 and 1000. Using if/else statements, the program will check to see if the user obtained number is higher/lower than the pre defined random number which is generated by the program. If the user makes a wrong guess, the program will re prompt the user to enter in a new number, where they will have a chance to enter in a new guess. Once the user finally guesses the correct answer, using a do/while loop, the program will ask if they want to play again. If the user selects yes, the game will start over, and a new random number will be generated. If the user selects no, the game will end.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

The "Random" Class Do/While Loop How To get Character Input Custom Setw/Setfill In Java





		
		
			I'm Thinking of a Number Between 1 and 1000...
			
Java
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Nov 19, 2012
//    Taken From: http://programmingnotes.org/
//    File:  GuessingGame.java
//    Description: Demonstrates a simple random number guessing game
// ============================================================================
import java.util.*;

public class GuessingGame
{
    // global variable declarations
    static Scanner cin = new Scanner(System.in);
    static Random rand = new Random(); // this is the call to the "Random" class

    public static void main(String[] args)
    {
        // declare & initialize variables
        char playAgain = 'y';
        int userInput = 0;
        int numGuesses = 0;
        int randomNumber = rand.nextInt(1000)+1;
        // ^ get a number from the random generator in the range of 1 - 1000

        System.out.println("Welcome to My Programming Notes' Java Program.\n");

        // display directions to user
        System.out.println("I'm thinking of a number between 1 and 1000. Go " +
                "ahead and make your first guess.\n");

        do { // this is the start of the do/while loop

            System.out.print(">> ");
            // get data from user
            userInput = cin.nextInt();
            System.out.println("");

            // increments the 'numGuesses' variable each time the user
            // gets the guess wrong
            ++numGuesses;

            // if user guess is too high, do this code
            if (userInput > randomNumber)
            {
                System.out.println("Too high! Think lower.");
            }

            // if user guess is too low, do this code
            else if (userInput < randomNumber)
            {
                System.out.println("Too low! Think higher.");
            }

            // if user guess is correct, do this code
            else
            {    // display data to user, prompt if user wants to play again
                System.out.print("You got it, and it only took you "
                    +numGuesses+" trys!\nWould you like to play again (y/n)? ");
                playAgain = cin.next().charAt(0);

                // if user wants to play again then re initialize the variables
                if (playAgain == 'y'|| playAgain == 'Y')
                {
                    // creates a line seperator if user wants to enter new data
                    System.out.println("");
                    setwRF("", 60, '-');

                    numGuesses = 0;
                    System.out.println("\n\nMake a guess (between 1-1000):\n");
                    // generate a new random number for the user to try & guess
                    randomNumber = rand.nextInt(1000)+1;
                }
            }
            System.out.println("");
        } while (playAgain == 'y' || playAgain == 'Y');
        // ^ do/while loop ends when user doesnt select 'Y'
        // display data to user
        System.out.println("Thanks for playing!!");
    }// end of main

    public static void setwRF(String str, int width, char fill)
    {
        System.out.print(str);
        for (int x = str.length(); x < width; ++x)
        {
            System.out.print(fill);
        }
    }// end of setwRF
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Nov 19, 2012
//    Taken From: http://programmingnotes.org/
//    File:  GuessingGame.java
//    Description: Demonstrates a simple random number guessing game
// ============================================================================
import java.util.*;
 
public class GuessingGame
{
    // global variable declarations
    static Scanner cin = new Scanner(System.in);
    static Random rand = new Random(); // this is the call to the "Random" class
 
    public static void main(String[] args)
    {
        // declare & initialize variables
        char playAgain = 'y';
        int userInput = 0;
        int numGuesses = 0;
        int randomNumber = rand.nextInt(1000)+1;
        // ^ get a number from the random generator in the range of 1 - 1000
 
        System.out.println("Welcome to My Programming Notes' Java Program.\n");
 
        // display directions to user
        System.out.println("I'm thinking of a number between 1 and 1000. Go " +
                "ahead and make your first guess.\n");
 
        do { // this is the start of the do/while loop
 
            System.out.print(">> ");
            // get data from user
            userInput = cin.nextInt();
            System.out.println("");
 
            // increments the 'numGuesses' variable each time the user
            // gets the guess wrong
            ++numGuesses;
 
            // if user guess is too high, do this code
            if (userInput > randomNumber)
            {
                System.out.println("Too high! Think lower.");
            }
 
            // if user guess is too low, do this code
            else if (userInput < randomNumber)
            {
                System.out.println("Too low! Think higher.");
            }
 
            // if user guess is correct, do this code
            else
            {    // display data to user, prompt if user wants to play again
                System.out.print("You got it, and it only took you "
                    +numGuesses+" trys!\nWould you like to play again (y/n)? ");
                playAgain = cin.next().charAt(0);
 
                // if user wants to play again then re initialize the variables
                if (playAgain == 'y'|| playAgain == 'Y')
                {
                    // creates a line seperator if user wants to enter new data
                    System.out.println("");
                    setwRF("", 60, '-');
 
                    numGuesses = 0;
                    System.out.println("\n\nMake a guess (between 1-1000):\n");
                    // generate a new random number for the user to try & guess
                    randomNumber = rand.nextInt(1000)+1;
                }
            }
            System.out.println("");
        } while (playAgain == 'y' || playAgain == 'Y');
        // ^ do/while loop ends when user doesnt select 'Y'
        // display data to user
        System.out.println("Thanks for playing!!");
    }// end of main
 
    public static void setwRF(String str, int width, char fill)
    {
        System.out.print(str);
        for (int x = str.length(); x < width; ++x)
        {
            System.out.print(fill);
        }
    }// end of setwRF
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output:

Welcome to My Programming Notes' Java Program.
I'm thinking of a number between 1 and 1000. Go ahead and make your first guess. >> 900 Too high! Think lower. >> 300 Too high! Think lower. >> 100 Too low! Think higher. >> 200 Too low! Think higher. >> 350 You got it, and it only took you 5 trys! Would you like to play again (y/n)? y ------------------------------------------------------------ Make a guess (between 1-1000): >> 300 Too low! Think higher. >> 600 Too high! Think lower. >> 500 Too high! Think lower. >> 400 You got it, and it only took you 4 trys! Would you like to play again (y/n)? n
Thanks for playing!!

C++ || Snippet – Simple Linked List Using Delete, Insert, & Display Functions

August 18, 2012 admin No comments

The following is sample code for a simple linked list, which implements the following functions: “Delete, Insert, and Display.”

The sample code provided on this page is a stripped down version of a more robust linked list class which was previously discussed on this site. Sample code for that can be found here.

It is recommended you check that out as the functions implemented within that class are very useful.





		
		
			Simple Linked List
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Aug 18, 2012
//    Taken From: http://programmingnotes.org/
//    File:  SimpleList.cpp
//    Description: Demonstrates the use of a simple linked list.
// ============================================================================
#include <iostream>
#include <string>
using namespace std;

struct node
{
    /* -- you can use different data types here
         -- instead of just a string
    char letter;
    int number;
    double fNumber;
    */
    string name;
    node* next;
};

// global variables
// this is the front of the list
node* head = NULL;

// function prototype
void Insert(string info);
void Delete(string info);
void Display();
void DestroyList();

int main()
{
    // if you want to insert data into the list
    // this is one way you can do it, using a 'temp' pointer
    node* temp = new node;
    temp->name = "My Programming Notes";
    temp->next = NULL;

    // set the head node to the data thats in the 'temp' pointer
    head = temp;

    // display data to the screen
    cout << head->name <<endl<<endl;

    // use the insert function to add new data to the list
    // NOTE: you could have also used the 'insert' function ^ above
    // to place data into the list
    Insert("Is An Awesome Site!");

    // insert more data into the list
    Insert("August");
    Display();

    // delete the selected text from the list
    Delete("August");
    Display();

    // destroy the current pointers in the list
    // after you are finished using them
    DestroyList();

    return 0;
}// end of main

void Insert(string info)
{
    node* newItem = new node;
    newItem->name = info;
    newItem->next = NULL;

    // if the list is empty, add new item to the front
    if(head == NULL)
    {
        head = newItem;
    }
    else // if the list isnt empty, add new item to the end
    {
        node* iter = head;
        while(iter->next != NULL)
        {
            iter = iter->next;
        }
        iter->next = newItem;
    }
}// end of Insert

void Delete(string info)
{
    node* iter = head;

    // if the list is empty, do nothing
    if(head == NULL)
    {
        return;
    }
    // delete the first item in the list
    else if(head->name == info)
    {
        head = head->next;
        delete iter;
    }
    // search the list until we find the desired item
    else
    {
        while(iter->next != NULL)
        {
            if(iter->next->name == info)
            {
                node* deleteNode = iter->next;
                iter->next = iter->next->next;
                delete deleteNode;
                break;
            }
            iter = iter->next;
        }
    }
}// end of Delete

void Display()
{
    node* iter = head;
    // traverse thru the list, displaying the
    // text at each node location
    while(iter != NULL)
    {
        cout<<iter->name<<endl;
        iter = iter->next;
    }
    cout<<endl;
}// end of Display

void DestroyList()
{
    if(head != NULL)
    {
        cout << "\n\nDestroying nodes...\n";
        while(head != NULL)
        {
            node* temp = head;
            cout << temp->name <<endl;
            head = head->next;
            delete temp;
        }
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Aug 18, 2012
//    Taken From: http://programmingnotes.org/
//    File:  SimpleList.cpp
//    Description: Demonstrates the use of a simple linked list.
// ============================================================================
#include <iostream>
#include <string>
using namespace std;
 
struct node
{
    /* -- you can use different data types here
         -- instead of just a string
    char letter;
    int number;
    double fNumber;
    */
    string name;
    node* next;
};
 
// global variables
// this is the front of the list
node* head = NULL;
 
// function prototype
void Insert(string info);
void Delete(string info);
void Display();
void DestroyList();
 
int main()
{
    // if you want to insert data into the list
    // this is one way you can do it, using a 'temp' pointer
    node* temp = new node;
    temp->name = "My Programming Notes";
    temp->next = NULL;
 
    // set the head node to the data thats in the 'temp' pointer
    head = temp;
 
    // display data to the screen
    cout << head->name <<endl<<endl;
 
    // use the insert function to add new data to the list
    // NOTE: you could have also used the 'insert' function ^ above
    // to place data into the list
    Insert("Is An Awesome Site!");
 
    // insert more data into the list
    Insert("August");
    Display();
 
    // delete the selected text from the list
    Delete("August");
    Display();
 
    // destroy the current pointers in the list
    // after you are finished using them
    DestroyList();
 
    return 0;
}// end of main
 
void Insert(string info)
{
    node* newItem = new node;
    newItem->name = info;
    newItem->next = NULL;
 
    // if the list is empty, add new item to the front
    if(head == NULL)
    {
        head = newItem;
    }
    else // if the list isnt empty, add new item to the end
    {
        node* iter = head;
        while(iter->next != NULL)
        {
            iter = iter->next;
        }
        iter->next = newItem;
    }
}// end of Insert
 
void Delete(string info)
{
    node* iter = head;
 
    // if the list is empty, do nothing
    if(head == NULL)
    {
        return;
    }
    // delete the first item in the list
    else if(head->name == info)
    {
        head = head->next;
        delete iter;
    }
    // search the list until we find the desired item
    else
    {
        while(iter->next != NULL)
        {
            if(iter->next->name == info)
            {
                node* deleteNode = iter->next;
                iter->next = iter->next->next;
                delete deleteNode;
                break;
            }
            iter = iter->next;
        }
    }
}// end of Delete
 
void Display()
{
    node* iter = head;
    // traverse thru the list, displaying the
    // text at each node location
    while(iter != NULL)
    {
        cout<<iter->name<<endl;
        iter = iter->next;
    }
    cout<<endl;
}// end of Display
 
void DestroyList()
{
    if(head != NULL)
    {
        cout << "\n\nDestroying nodes...\n";
        while(head != NULL)
        {
            node* temp = head;
            cout << temp->name <<endl;
            head = head->next;
            delete temp;
        }
    }
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

My Programming Notes
My Programming Notes Is An Awesome Site! August [DELETE THE TEXT "AUGUST"] My Programming Notes Is An Awesome Site!
Destroying nodes... My Programming Notes Is An Awesome Site!

C++ || Snippet – Palindrome Checker Using A Stack & Queue

July 22, 2012 admin No comments

Click Here For Updated Version Of Program

This page consists of a sample program which demonstrates how to use a stack and a queue to test for a palindrome. This program is great practice for understanding how the two data structures work.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Structs Classes Template Classes - What Are They? Stacks Queues LIFO - Last In First Out FIFO - First In First Out #include 'SingleQueue.h' #include 'ClassStackListType.h'

This program first asks the user to enter in text which they wish to compare for similarity. The data is then saved into the system using the “enqueue” and “push” functions available within the queue and stack classes. After the data is obtained, a while loop is used to iterate through both classes, checking to see if the characters at each location within both classes are the same. If the text within both classes are the same, it is a palindrome.

NOTE: This program uses two custom template.h classes. To obtain the code for both class, click here and here.





		
		
			Palindrome Checker Using Stack & Queue
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 22, 2012
//    Taken From: http://programmingnotes.org/
//    File:  palindrome.cpp
//    Description: Demonstrates a palindrome checker using a stack & queue
// ============================================================================
#include <iostream>
#include <cctype>
#include "SingleQueue.h"
#include "ClassStackListType.h"
using namespace std;

int main()
{
    // declare variable
    char singleChar = ' ';
    bool isPalindrome = true;
    SingleQueue<char> queue;
    StackListType<char> stack;

    // get data from user, then place them into the
    // queue and stack for storage. This loop also
    // displays the user input back to the screen via cout
    cout <<"Enter in some text to see if its a palindrome: ";
    while(cin.get(singleChar) && singleChar != '\n')
    {
        cout<<singleChar;
        queue.EnQueue(toupper(singleChar));
        stack.Push(toupper(singleChar));
    }

    // determine if the string is a palindrome
    while((!queue.IsEmpty() && !stack.IsEmpty())
        && isPalindrome)
    {
        if(queue.Front() != stack.Top())
        {
            isPalindrome = false;
        }
        else
        {
            queue.DeQueue();
            stack.Pop();
        }
    }

    // display results to the screen
    if(isPalindrome)
    {
        cout<<" is a palindrome!\n";
    }
    else
    {
        cout<<" is NOT a palindrome..\n";
    }

    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 22, 2012
//    Taken From: http://programmingnotes.org/
//    File:  palindrome.cpp
//    Description: Demonstrates a palindrome checker using a stack & queue
// ============================================================================
#include <iostream>
#include <cctype>
#include "SingleQueue.h"
#include "ClassStackListType.h"
using namespace std;
 
int main()
{
    // declare variable
    char singleChar = ' ';
    bool isPalindrome = true;
    SingleQueue<char> queue;
    StackListType<char> stack;
 
    // get data from user, then place them into the
    // queue and stack for storage. This loop also
    // displays the user input back to the screen via cout
    cout <<"Enter in some text to see if its a palindrome: ";
    while(cin.get(singleChar) && singleChar != '\n')
    {
        cout<<singleChar;
        queue.EnQueue(toupper(singleChar));
        stack.Push(toupper(singleChar));
    }
 
    // determine if the string is a palindrome
    while((!queue.IsEmpty() && !stack.IsEmpty())
        && isPalindrome)
    {
        if(queue.Front() != stack.Top())
        {
            isPalindrome = false;
        }
        else
        {
            queue.DeQueue();
            stack.Pop();
        }
    }
 
    // display results to the screen
    if(isPalindrome)
    {
        cout<<" is a palindrome!\n";
    }
    else
    {
        cout<<" is NOT a palindrome..\n";
    }
 
    return 0;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output
(Note: The code was compiled 2 separate times to demonstrate different output)

====== RUN 1 ======
Enter in some text to see if its a palindrome: StEP on No pETS StEP on No pETS is a palindrome! ====== RUN 2 ====== Enter in some text to see if its a palindrome: Hello World
Hello World is NOT a palindrome..

C++ || Convert Numbers To Words Using A Switch Statement

July 21, 2012 admin No comments

This program demonstrates more practice using arrays and switch statements.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Integer Arrays Cin.get Isdigit For loops While Loops Switch Statements - How To Use

Using “cin.get(),” this program first asks the user to enter in a number (one at a time) that they wish to translate into words. If the text which was entered into the system is a number, the program will save the user input into an integer array. If the text is not a number, the input is discarded. After integer data is obtained, a for loop is used to traverse the integer array, passing the data to a switch statement, which translates the number to text.

This program is very simple, so it does not have the ability to display any number prefixes. As a result, if the number “1858” was entered into the system, the program would output the converted text: “One Eight Five Eight.”





		
		
			Convert Numbers To Words
			
C++
			
			#include <iostream>
#include <cctype>
using namespace std;
 
int main()
{
	// declare variables
	int numberArry[50];
	int numElems=0;
	char singleNum=' ';

	// ask the user for a number
	cout<<"Enter number: ";

	// get data from the user, one character at a time
	while(cin.get(singleNum) && singleNum != 'n')
	{
		// only numbers will be saved into the array, everything
		// else is ignored
		if(isdigit(singleNum))
		{
			// this converts a char into an integer using ascii values
			numberArry[numElems] = (singleNum)-'0'; 
			++numElems;
		}
	}

	cout<<endl;

	// using the data from the array, display the
	// numbers to the screen using a switch statement
	for(int index=0; index < numElems; ++index)
	{
		switch(numberArry[index])
		{
			case 0 :
				cout<<"Zero ";
				break;
			case 1 : 
				cout<<"One ";
				break;
			case 2: 
				cout<<"Two ";
				break;
			case 3: 
				cout<<"Three ";
				break;
			case 4:
				cout<<"Four ";
				break;
			case 5:
				cout<<"Five ";
				break;
			case 6:
				cout<<"Six ";
				break;
			case 7:
				cout<<"Seven ";
				break;
			case 8:
				cout<<"Eight ";
				break;
			case 9:
				cout<<"Nine ";
				break;
			default:
				cout<<"nERROR!n";
				break;
		}
	}
	cout<<endl;

	return 0;
}// http://programmingnotes.org/
			
				
					
				
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						#include <iostream>
#include <cctype>
using namespace std;
 
int main()
{
	// declare variables
	int numberArry[50];
	int numElems=0;
	char singleNum=' ';
 
	// ask the user for a number
	cout<<"Enter number: ";
 
	// get data from the user, one character at a time
	while(cin.get(singleNum) && singleNum != 'n')
	{
		// only numbers will be saved into the array, everything
		// else is ignored
		if(isdigit(singleNum))
		{
			// this converts a char into an integer using ascii values
			numberArry[numElems] = (singleNum)-'0'; 
			++numElems;
		}
	}
 
	cout<<endl;
 
	// using the data from the array, display the
	// numbers to the screen using a switch statement
	for(int index=0; index < numElems; ++index)
	{
		switch(numberArry[index])
		{
			case 0 :
				cout<<"Zero ";
				break;
			case 1 : 
				cout<<"One ";
				break;
			case 2: 
				cout<<"Two ";
				break;
			case 3: 
				cout<<"Three ";
				break;
			case 4:
				cout<<"Four ";
				break;
			case 5:
				cout<<"Five ";
				break;
			case 6:
				cout<<"Six ";
				break;
			case 7:
				cout<<"Seven ";
				break;
			case 8:
				cout<<"Eight ";
				break;
			case 9:
				cout<<"Nine ";
				break;
			default:
				cout<<"nERROR!n";
				break;
		}
	}
	cout<<endl;
 
	return 0;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output
Note: The code was compiled four separate times to display different output

======= Run #1 =======
Enter number: 77331 Seven Seven Three Three One ======= Run #2 ======= Enter number: 234-43-1275 Two Three Four Four Three One Two Seven Five ======= Run #3 ======= Enter number: 1(800) 123-5678 One Eight Zero Zero One Two Three Five Six Seven Eight ======= Run #4 ======= Enter number: This 34 Is 24 A 5 Number 28
Three Four Two Four Five Two Eight

C++ || Char Array – Palindrome Number Checker Using A Character Array, Strlen, Strcpy, & Strcmp

July 10, 2012 admin No comments

The following is a palindromic number checking program, which demonstrates more use of character array’s, Strlen, & Strcmp.

Want sample code for a palindrome checker which works for numbers and words? Click here.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Character Arrays How to reverse a character array Palindrome - What is it? Strlen Strcpy Strcmp Isdigit Atoi - Convert a char array to a number Do/While Loops For Loops

This program first asks the user to enter a number that they wish to compare for similarity. If the number which was entered into the system is a palindrome, the program will prompt a message to the user via cout. This program determines similarity by using the strcmp function to compare two arrays together. Using a for loop, this program also demonstrates how to reverse a character array, aswell as demonstrates how to determine if the text contained in a character array is a number or not.

This program will repeatedly prompt the user for input until an “exit code” is obtained. The designated exit code in this program is the number 0 (zero). So the program will not stop asking for user input until the number 0 is entered into the program.





		
		
			Palindrome Number Checker Using A Char Array
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 10, 2012
//    Taken From: http://programmingnotes.org/
//    File:  palindrome.cpp
//    Description: Palindrome number checker
// ============================================================================
#include <iostream>
#include <cctype>
#include <cstring>
#include <cstdlib>
using namespace std;

// function prototypes
void Reverse(char arry[]);
bool IsArryANum(char arry[]);

// constant, which is the exit value 
const char* EXIT_VALUE = "0";

int main()
{
    // declare variables
    char arry[80];
    char arryReversed[80];
    
    do{// get data from user using do/while loop
        cout<<"\nEnter a positive integer, or ("<<EXIT_VALUE<<") to exit: ";
        
        cin >> arry;
        
        if(atoi(arry) < 0) // check for negative numbers
        {
            cout <<"\n*** Error: "<<arry<<" must be greater than zero\n";
        }
        else if(!IsArryANum(arry)) // check for any letters 
        {
            cout <<"\n*** Error: "<<arry<<" is not an integer\n";
        }
        else if(strcmp(EXIT_VALUE, arry) == 0) // check for "exit code"
        {
            cout <<"\nExiting program...\n";
        }
        else // if all else is good, determine if number is a palindrome 
        {
            // copy the user input from the first array (arry)
            // into the second array (arryReversed)
            strcpy(arryReversed, arry);

            // function call to reverse the contents inside the
            // "arryReversed" array to check for similarity
            Reverse(arryReversed);
            
            cout <<endl<<arry;

            // use strcmp to determine if the two arrays are the same
            if(strcmp(arryReversed, arry) == 0)
            {
                cout <<" is a Palindrome..\n";
            }
            else
            {
                cout <<" is NOT a Palindrome!\n";
            }
        }
    }while(strcmp(EXIT_VALUE, arry) != 0); // keep going until user enters the exit value

    cout <<"\nBYE!\n";
    
    return 0;
}// end of main

void Reverse(char arry[])
{
    // get the length of the current word in the array index
    int length = strlen(arry)-1;
    
    // increment thru each letter within the current char array index
    // reversing the order of the array
    for (int currentChar=0; currentChar < length; --length, ++currentChar)
    {
        // copy 1st letter in the array index into temp
        char temp = arry[currentChar];
        // copy last letter in the array index into the 1st array index
        arry[currentChar] = arry[length];
        // copy temp into last array index
        arry[length] = temp;
    }
}// end of Reverse

bool IsArryANum(char arry[])
{
    // LOOP UNTIL U REACH THE NULL CHARACTER,
    // AKA THE END OF THE CHAR ARRAY
    for(int x=0; arry[x]!='\0'; ++x)
    {               
        // if the current char isnt a number,
        // exit the loop & return false
        if(!isdigit(arry[x])) 
        {
            return false;
        }
    }
    return true;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 10, 2012
//    Taken From: http://programmingnotes.org/
//    File:  palindrome.cpp
//    Description: Palindrome number checker
// ============================================================================
#include <iostream>
#include <cctype>
#include <cstring>
#include <cstdlib>
using namespace std;
 
// function prototypes
void Reverse(char arry[]);
bool IsArryANum(char arry[]);
 
// constant, which is the exit value 
const char* EXIT_VALUE = "0";
 
int main()
{
    // declare variables
    char arry[80];
    char arryReversed[80];
    
    do{// get data from user using do/while loop
        cout<<"\nEnter a positive integer, or ("<<EXIT_VALUE<<") to exit: ";
        
        cin >> arry;
        
        if(atoi(arry) < 0) // check for negative numbers
        {
            cout <<"\n*** Error: "<<arry<<" must be greater than zero\n";
        }
        else if(!IsArryANum(arry)) // check for any letters 
        {
            cout <<"\n*** Error: "<<arry<<" is not an integer\n";
        }
        else if(strcmp(EXIT_VALUE, arry) == 0) // check for "exit code"
        {
            cout <<"\nExiting program...\n";
        }
        else // if all else is good, determine if number is a palindrome 
        {
            // copy the user input from the first array (arry)
            // into the second array (arryReversed)
            strcpy(arryReversed, arry);
 
            // function call to reverse the contents inside the
            // "arryReversed" array to check for similarity
            Reverse(arryReversed);
            
            cout <<endl<<arry;
 
            // use strcmp to determine if the two arrays are the same
            if(strcmp(arryReversed, arry) == 0)
            {
                cout <<" is a Palindrome..\n";
            }
            else
            {
                cout <<" is NOT a Palindrome!\n";
            }
        }
    }while(strcmp(EXIT_VALUE, arry) != 0); // keep going until user enters the exit value
 
    cout <<"\nBYE!\n";
    
    return 0;
}// end of main
 
void Reverse(char arry[])
{
    // get the length of the current word in the array index
    int length = strlen(arry)-1;
    
    // increment thru each letter within the current char array index
    // reversing the order of the array
    for (int currentChar=0; currentChar < length; --length, ++currentChar)
    {
        // copy 1st letter in the array index into temp
        char temp = arry[currentChar];
        // copy last letter in the array index into the 1st array index
        arry[currentChar] = arry[length];
        // copy temp into last array index
        arry[length] = temp;
    }
}// end of Reverse
 
bool IsArryANum(char arry[])
{
    // LOOP UNTIL U REACH THE NULL CHARACTER,
    // AKA THE END OF THE CHAR ARRAY
    for(int x=0; arry[x]!='\0'; ++x)
    {               
        // if the current char isnt a number,
        // exit the loop & return false
        if(!isdigit(arry[x])) 
        {
            return false;
        }
    }
    return true;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

Enter a positive integer, or (0) to exit: L33T
*** error: "L33T" is not an integer Enter a positive integer, or (0) to exit: -728 *** error: -728 must be greater than zero Enter a positive integer, or (0) to exit: 1858 1858 is NOT a Palindrome! Enter a positive integer, or (0) to exit: 7337 7337 is a Palindrome.. Enter a positive integer, or (0) to exit: 0 Exiting program...
BYE!

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