January 2014 – My Programming Notes

Monthly Archives: January 2014

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

January 31, 2014 admin 1 Comment

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++ || Simple Tokenizer Lexer Using A Finite State Machine

January 29, 2014 admin 1 Comment

The following is sample code which demonstrates the implementation of a simple Lexer using a table driven Finite State Machine.

In its simplest form, a Finite State Machine is a procedure that can: (1) store the status of an event, (2) can operate on new (or existing) input to change the status of an event, and (3) can cause an action to take place (based on the input change) for the particular event being examined.

State machines usually adhere to the following basic principles:

• Has an initial state or record of something stored someplace • Has a set of possible input events • Has a set of new states that may result from the input • Has a set of possible actions or output events that result from a new state

Finite state machines usually have a limited or finite number of possible states. The Finite State Machine implemented on this page has 6 transition states. Those transition states has the ability to isolate tokens from a given input string, based on characteristics defined in the transition state table.

The machine was implemented with compiler construction in mind, resulting in the grammar for the 6 transition states to resemble that of many popular programming languages.

The transition table defined in this program can be further fine tuned by allowing the states to accept or reject different parameters, and/or by adding more transition states. Tuning the parameters in the state transition table allows you to change the behavior of the state machine without having the need to alter the Finite State Machine Algorithm (the “Lexer” function) much at all.

NOTE: The example on this page uses a sample input file. Click here to download the file.





		
		
			Simple Lexer Using A Finite State Machine
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 29, 2014
//    Taken From: http://programmingnotes.org/
//    File: FSM.cpp
//    Description: The following demonstrates the implementation of a simple
//      Lexer using a table driven Finite State Machine.
// ============================================================================
#include <iostream>
#include <cstdlib>
#include <cctype>
#include <string>
#include <vector>
#include <fstream>
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,
    OPERATOR,
    STRING,
    UNKNOWN,
    SPACE
};

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

    -- You can tune this table to make the states accept or reject different
      parameters, thus changing its behavior. More states can be added to
      this table.
                           integer,  real,  operator,  string,  unknown,  space */
int stateTable[][7] = {{0, INTEGER,  REAL,  OPERATOR,  STRING, UNKNOWN,  SPACE},
/* STATE 1 */   {INTEGER,  INTEGER,  REAL,   REJECT,   REJECT,  REJECT,  REJECT},
/* STATE 2 */   {REAL,       REAL,  UNKNOWN, REJECT,   REJECT,  REJECT,  REJECT},
/* STATE 3 */   {OPERATOR,  REJECT, REJECT,  REJECT,   STRING,  REJECT,  REJECT},
/* STATE 4 */   {STRING,    STRING, REJECT,  STRING,   STRING,  REJECT,  REJECT},
/* STATE 5 */   {UNKNOWN,  UNKNOWN, UNKNOWN, UNKNOWN,  UNKNOWN, UNKNOWN, REJECT},
/* STATE 6 */   {SPACE,     REJECT, REJECT,  REJECT,   REJECT,  REJECT,  REJECT}};


// struct to hold token information
struct TokenType
{
    string token;
    int lexeme;
    string lexemeName;
};

// function prototypes
vector<TokenType> Lexer(string expression);
int Get_FSM_Col(char currentChar);
string GetLexemeName(int lexeme);

int main()
{
    // declare variables
    ifstream infile;
    string fileName = "";
    string expression = "";
    vector<TokenType> tokens;

    // get data from user
    cout<<"\nPlease enter the name of the file: ";
    getline(cin, fileName);

    infile.open(fileName.c_str());

    if(infile.fail())
    {
        cout<<"\n** ERROR - the file \""<<fileName<<"\" cannot be found!\n\n";
        exit(1);
    }

    // use a loop to scan each line in the file
    while(getline(infile, expression))
    {
        // use the "Lexer" function to isolate integer, real, operator,
        // string, and unknown tokens
        tokens = Lexer(expression);

        // display the tokens to the screen
        for(unsigned x = 0; x < tokens.size(); ++x)
        {
            cout<<tokens[x].lexemeName<<"  \t"
                <<tokens[x].token<<endl;
        }
    }

    infile.close();

    return 0;
}// end of main

/**
* FUNCTION: Lexer
* USE: Parses the "expression" string using the Finite State Machine to
*     isolate each individual token and lexeme name in the expression.
* @param expression - A std::string containing text.
* @return - Returns a vector containing the tokens found in the string
*/
vector<TokenType> Lexer(string expression)
{
    TokenType access;
    vector<TokenType> tokens;
    char currentChar = ' ';
    int col = REJECT;
    int currentState = REJECT;
    int prevState = REJECT;
    string currentToken = "";

    // use an FSM to parse the expression
    for(unsigned x = 0; x < expression.length();)
    {
        currentChar = expression[x];

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

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

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

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

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

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

          THIS IS WHERE WE CHECK FOR A SUCESSFUL PARSE
           - If the current state of the expression == REJECT
             (the starting state), then we have sucessfully parsed
             a token.

            - ELSE we continue trying to find a sucessful token

            =================================================== */
        if(currentState == REJECT)
        {
            if(prevState != SPACE) // we dont care about whitespace
            {
                access.token = currentToken;
                access.lexeme = prevState;
                access.lexemeName = GetLexemeName(access.lexeme);
                tokens.push_back(access);
            }
            currentToken = "";
        }
        else
        {
            currentToken += currentChar;
            ++x;
        }
        prevState = currentState;

    }
    // this ensures the last token gets saved when
    // we reach the end of the loop (if a valid token exists)
    if(currentState != SPACE && currentToken != "")
    {// ^^ we dont care about whitespace
        access.token = currentToken;
        access.lexeme = currentState;
        access.lexemeName = GetLexemeName(access.lexeme);
        tokens.push_back(access);
    }
    return tokens;
}// end of Lexer

/**
* FUNCTION: Get_FSM_Col
* USE: Determines the state of the type of character being examined.
* @param currentChar - A character.
* @return - Returns the state of the type of character being examined.
*/
int Get_FSM_Col(char currentChar)
{
    // 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 characters
    else if(isalpha(currentChar))
    {
        return STRING;
    }

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

/**
* FUNCTION: GetLexemeName
* USE: Returns the string equivalent of an integer lexeme token type.
* @param lexeme - An integer lexeme token type.
* @return - An std::string string representing the name of the integer
*        lexeme token type.
*/
string GetLexemeName(int lexeme)
{
    switch(lexeme)
    {
        case INTEGER:
           return "INTEGER";
           break;
        case REAL:
           return "REAL  ";
           break;
        case OPERATOR:
           return "OPERATOR";
           break;
        case STRING:
           return "STRING";
           break;
        case UNKNOWN:
           return "UNKNOWN";
           break;
        case SPACE:
           return "SPACE";
           break;
        default:
           return "ERROR";
           break;
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jan 29, 2014
//    Taken From: http://programmingnotes.org/
//    File: FSM.cpp
//    Description: The following demonstrates the implementation of a simple
//      Lexer using a table driven Finite State Machine.
// ============================================================================
#include <iostream>
#include <cstdlib>
#include <cctype>
#include <string>
#include <vector>
#include <fstream>
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,
    OPERATOR,
    STRING,
    UNKNOWN,
    SPACE
};
 
/* This is the Finite State Machine Table
    -- The zero represents a place holder, so the row in the array starts on
      row 1 instead of 0.
 
    -- You can tune this table to make the states accept or reject different
      parameters, thus changing its behavior. More states can be added to
      this table.
                           integer,  real,  operator,  string,  unknown,  space */
int stateTable[][7] = {{0, INTEGER,  REAL,  OPERATOR,  STRING, UNKNOWN,  SPACE},
/* STATE 1 */   {INTEGER,  INTEGER,  REAL,   REJECT,   REJECT,  REJECT,  REJECT},
/* STATE 2 */   {REAL,       REAL,  UNKNOWN, REJECT,   REJECT,  REJECT,  REJECT},
/* STATE 3 */   {OPERATOR,  REJECT, REJECT,  REJECT,   STRING,  REJECT,  REJECT},
/* STATE 4 */   {STRING,    STRING, REJECT,  STRING,   STRING,  REJECT,  REJECT},
/* STATE 5 */   {UNKNOWN,  UNKNOWN, UNKNOWN, UNKNOWN,  UNKNOWN, UNKNOWN, REJECT},
/* STATE 6 */   {SPACE,     REJECT, REJECT,  REJECT,   REJECT,  REJECT,  REJECT}};
 
 
// struct to hold token information
struct TokenType
{
    string token;
    int lexeme;
    string lexemeName;
};
 
// function prototypes
vector<TokenType> Lexer(string expression);
int Get_FSM_Col(char currentChar);
string GetLexemeName(int lexeme);
 
int main()
{
    // declare variables
    ifstream infile;
    string fileName = "";
    string expression = "";
    vector<TokenType> tokens;
 
    // get data from user
    cout<<"\nPlease enter the name of the file: ";
    getline(cin, fileName);
 
    infile.open(fileName.c_str());
 
    if(infile.fail())
    {
        cout<<"\n** ERROR - the file \""<<fileName<<"\" cannot be found!\n\n";
        exit(1);
    }
 
    // use a loop to scan each line in the file
    while(getline(infile, expression))
    {
        // use the "Lexer" function to isolate integer, real, operator,
        // string, and unknown tokens
        tokens = Lexer(expression);
 
        // display the tokens to the screen
        for(unsigned x = 0; x < tokens.size(); ++x)
        {
            cout<<tokens[x].lexemeName<<"  \t"
                <<tokens[x].token<<endl;
        }
    }
 
    infile.close();
 
    return 0;
}// end of main
 
/**
* FUNCTION: Lexer
* USE: Parses the "expression" string using the Finite State Machine to
*     isolate each individual token and lexeme name in the expression.
* @param expression - A std::string containing text.
* @return - Returns a vector containing the tokens found in the string
*/
vector<TokenType> Lexer(string expression)
{
    TokenType access;
    vector<TokenType> tokens;
    char currentChar = ' ';
    int col = REJECT;
    int currentState = REJECT;
    int prevState = REJECT;
    string currentToken = "";
 
    // use an FSM to parse the expression
    for(unsigned x = 0; x < expression.length();)
    {
        currentChar = expression[x];
 
        // get the column number for the current character
        col = Get_FSM_Col(currentChar);
 
        /* ========================================================
 
            THIS IS WHERE WE CHECK THE FINITE STATE MACHINE TABLE
               USING THE "col" VARIABLE FROM ABOVE ^
 
          ========================================================= */
 
        // get the current state of the expression
        currentState = stateTable[currentState][col];
 
        /* ===================================================
 
          THIS IS WHERE WE CHECK FOR A SUCESSFUL PARSE
           - If the current state of the expression == REJECT
             (the starting state), then we have sucessfully parsed
             a token.
 
            - ELSE we continue trying to find a sucessful token
 
            =================================================== */
        if(currentState == REJECT)
        {
            if(prevState != SPACE) // we dont care about whitespace
            {
                access.token = currentToken;
                access.lexeme = prevState;
                access.lexemeName = GetLexemeName(access.lexeme);
                tokens.push_back(access);
            }
            currentToken = "";
        }
        else
        {
            currentToken += currentChar;
            ++x;
        }
        prevState = currentState;
 
    }
    // this ensures the last token gets saved when
    // we reach the end of the loop (if a valid token exists)
    if(currentState != SPACE && currentToken != "")
    {// ^^ we dont care about whitespace
        access.token = currentToken;
        access.lexeme = currentState;
        access.lexemeName = GetLexemeName(access.lexeme);
        tokens.push_back(access);
    }
    return tokens;
}// end of Lexer
 
/**
* FUNCTION: Get_FSM_Col
* USE: Determines the state of the type of character being examined.
* @param currentChar - A character.
* @return - Returns the state of the type of character being examined.
*/
int Get_FSM_Col(char currentChar)
{
    // 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 characters
    else if(isalpha(currentChar))
    {
        return STRING;
    }
 
    // check for operators
    else if(ispunct(currentChar))
    {
        return OPERATOR;
    }
    return UNKNOWN;
}// end of Get_FSM_Col
 
/**
* FUNCTION: GetLexemeName
* USE: Returns the string equivalent of an integer lexeme token type.
* @param lexeme - An integer lexeme token type.
* @return - An std::string string representing the name of the integer
*        lexeme token type.
*/
string GetLexemeName(int lexeme)
{
    switch(lexeme)
    {
        case INTEGER:
           return "INTEGER";
           break;
        case REAL:
           return "REAL  ";
           break;
        case OPERATOR:
           return "OPERATOR";
           break;
        case STRING:
           return "STRING";
           break;
        case UNKNOWN:
           return "UNKNOWN";
           break;
        case SPACE:
           return "SPACE";
           break;
        default:
           return "ERROR";
           break;
    }
}// 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.

NOTE: The example on this page uses a sample input file. Click here to download the file.

The following is sample output.





		
		
			Please enter the name of the file: FiniteStateMachine_programmingnotes_freeweq_com.txt

STRING  	Rat12F
STRING  	Function
STRING  	function
STRING  	Identifier
OPERATOR  	(
OPERATOR  	)
OPERATOR  	:
OPERATOR  	:
OPERATOR  	;
OPERATOR  	,
OPERATOR  	{
OPERATOR  	}
OPERATOR  	=
OPERATOR  	[
OPERATOR  	]
STRING  	int
STRING  	boolean
STRING  	real
STRING  	If
STRING  	if
STRING  	else
STRING  	fi
STRING  	while
STRING  	Return
STRING  	return
OPERATOR  	;
STRING  	printf
STRING  	scanf
OPERATOR  	(
STRING  	IDs
OPERATOR  	)
OPERATOR  	;
OPERATOR  	=
OPERATOR  	=
OPERATOR  	!
OPERATOR  	=
OPERATOR  	>
OPERATOR  	>
OPERATOR  	<
OPERATOR  	=
OPERATOR  	>
OPERATOR  	<
OPERATOR  	=
OPERATOR  	+
OPERATOR  	-
OPERATOR  	*
OPERATOR  	/
OPERATOR  	/
OPERATOR  	-
STRING  	true
STRING  	false
INTEGER  	123
INTEGER  	0000
REAL    	13.456
REAL    	.567
UNKNOWN  	12.45.67.
STRING  	a_c__4t
STRING  	a____t
STRING  	x
STRING  	x56
STRING  	_fgt
OPERATOR  	%
OPERATOR  	&
OPERATOR  	/
OPERATOR  	*
STRING  	Middle
OPERATOR  	*
OPERATOR  	/
OPERATOR  	/
OPERATOR  	*
STRING  	end
OPERATOR  	*
OPERATOR  	/
INTEGER  	67
STRING  	yu
			
				
					
				
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						Please enter the name of the file: FiniteStateMachine_programmingnotes_freeweq_com.txt
 
STRING  	Rat12F
STRING  	Function
STRING  	function
STRING  	Identifier
OPERATOR  	(
OPERATOR  	)
OPERATOR  	:
OPERATOR  	:
OPERATOR  	;
OPERATOR  	,
OPERATOR  	{
OPERATOR  	}
OPERATOR  	=
OPERATOR  	[
OPERATOR  	]
STRING  	int
STRING  	boolean
STRING  	real
STRING  	If
STRING  	if
STRING  	else
STRING  	fi
STRING  	while
STRING  	Return
STRING  	return
OPERATOR  	;
STRING  	printf
STRING  	scanf
OPERATOR  	(
STRING  	IDs
OPERATOR  	)
OPERATOR  	;
OPERATOR  	=
OPERATOR  	=
OPERATOR  	!
OPERATOR  	=
OPERATOR  	>
OPERATOR  	>
OPERATOR  	<
OPERATOR  	=
OPERATOR  	>
OPERATOR  	<
OPERATOR  	=
OPERATOR  	+
OPERATOR  	-
OPERATOR  	*
OPERATOR  	/
OPERATOR  	/
OPERATOR  	-
STRING  	true
STRING  	false
INTEGER  	123
INTEGER  	0000
REAL    	13.456
REAL    	.567
UNKNOWN  	12.45.67.
STRING  	a_c__4t
STRING  	a____t
STRING  	x
STRING  	x56
STRING  	_fgt
OPERATOR  	%
OPERATOR  	&
OPERATOR  	/
OPERATOR  	*
STRING  	Middle
OPERATOR  	*
OPERATOR  	/
OPERATOR  	/
OPERATOR  	*
STRING  	end
OPERATOR  	*
OPERATOR  	/
INTEGER  	67
STRING  	yu

C++ || Snippet – How To Send Text Over A Network Using A TCP Connection

January 08, 2014 admin No comments

The following is sample code which demonstrates the use of the “socket“, “connect“, “bind“, “read“, and “write” function calls for interprocess communication over a network on Unix based systems.

The following example demonstrates a simple network application in which a client sends text to a server, and the server replies (sends text) back to the client. This program demonstrates communication between two programs using a TCP connection.

Click here to examine the UDP version.

Note: The server program must be ran before the client program!

=== 1. SERVER ===





		
		
			IPC Networking - TCP Server
			
C++
			
			// ============================================================================
//   Author: Kenneth Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ServerTCP.cpp
//   Description: This program implements a simple network application in
//     which a client sends text to a server and the server replies back to the
//     client. This is the server program, and has the following functionality:
//       1. Listen for incoming connections on a specified port.
//       2. When a client tries to connect, the connection is accepted.
//       3. When a connection is created, text is received from the client.
//       4. Text is sent back to the client from the server.
//       5. Close the connection and go back to waiting for more connections.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
using namespace std;

// Compile & Run
// g++ ServerTCP.cpp -o ServerTCP
// ./ServerTCP 1234

// the maximum size for sending/receiving text
const int MSG_SIZE = 100;

int main(int argc, char* argv[])
{
    // declare variables
    // the port number
    int port = -1;

    // the integer to store the file descriptor number
    // which will represent a socket on which the server
    // will be listening
    int listenfd = -1;

    // the file descriptor representing the connection to the client
    int connfd = -1;

    // the number of bytes read
    int numRead = -1;

    // the buffer to store text
    char data[MSG_SIZE];

    // the structures representing the server and client
    // addresses respectively
    sockaddr_in serverAddr, cliAddr;

    // stores the size of the client's address
    socklen_t cliLen = sizeof(cliAddr);

    // make sure the user has provided the port number to listen on
    if(argc < 2)
    {
        cerr<<"\n** ERROR NOT ENOUGH ARGS!\n"
            <<"USAGE: "<<argv[0]<<" <SERVER PORT #>\n\n";
        exit(1);
    }

    // get the port number
    port = atoi(argv[1]);

    // make sure that the port is within a valid range
    if(port < 0 || port > 65535)
    {
        cerr<<"Invalid port number\n";
        exit(1);
    }

    // create a socket that uses
    // IPV4 addressing scheme (AF_INET),
    // Supports reliable data transfer (SOCK_STREAM),
    // and choose the default protocol that provides
    // reliable service (i.e. 0); usually TCP
    if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket");
        exit(1);
    }

    // set the structure to all zeros
    memset(&serverAddr, 0, sizeof(serverAddr));

    // convert the port number to network representation
    serverAddr.sin_port = htons(port);

    // set the server family
    serverAddr.sin_family = AF_INET;

    // retrieve packets without having to know your IP address,
    // and retrieve packets from all network interfaces if the
    // machine has multiple ones
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);

    // associate the address with the socket
    if(bind(listenfd, (sockaddr *) &serverAddr, sizeof(serverAddr)) < 0)
    {
        perror("bind");
        exit(1);
    }

    // listen for connections on socket listenfd.
    // allow no more than 100 pending clients.
    if(listen(listenfd, 100) < 0)
    {
        perror("listen");
        exit(1);
    }

    cerr<<"\nServer started!\n";

    // wait forever for connections to come
    while(true)
    {
        cerr<<"\nWaiting for someone to connect..\n";

        // a structure to store the client address
        if((connfd = accept(listenfd, (sockaddr *)&cliAddr, &cliLen)) < 0)
        {
            perror("accept");
            exit(1);
        }

        // receive whatever the client sends
        if((numRead = read(connfd, data, sizeof(data))) < 0)
        {
            perror("read");
            exit(1);
        }

        // NULL terminate the received string
        data[numRead] = '\0';

        cerr<<"\nRECEIVED: '"<<data<<"' from the client\n";
        //cerr<<"Bytes read: "<<numRead<<endl;

        // set the array to all zeros
        memset(&data, 0, sizeof(data));

        // retrieve the time
        time_t rawtime;
        time(&rawtime);
        struct tm* timeinfo;
        timeinfo = localtime(&rawtime);
        strftime(data, sizeof(data),"%a, %b %d %Y, %I:%M:%S %p", timeinfo);

        cerr<<"\nSENDING: '"<<data<<"' to the client\n";

        // send the client a message
        if(write(connfd, data, strlen(data)+1) < 0)
        {
            perror("write");
            exit(1);
        }

        // close the socket
        close(connfd);
    }

    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author: Kenneth Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ServerTCP.cpp
//   Description: This program implements a simple network application in
//     which a client sends text to a server and the server replies back to the
//     client. This is the server program, and has the following functionality:
//       1. Listen for incoming connections on a specified port.
//       2. When a client tries to connect, the connection is accepted.
//       3. When a connection is created, text is received from the client.
//       4. Text is sent back to the client from the server.
//       5. Close the connection and go back to waiting for more connections.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
using namespace std;
 
// Compile & Run
// g++ ServerTCP.cpp -o ServerTCP
// ./ServerTCP 1234
 
// the maximum size for sending/receiving text
const int MSG_SIZE = 100;
 
int main(int argc, char* argv[])
{
    // declare variables
    // the port number
    int port = -1;
 
    // the integer to store the file descriptor number
    // which will represent a socket on which the server
    // will be listening
    int listenfd = -1;
 
    // the file descriptor representing the connection to the client
    int connfd = -1;
 
    // the number of bytes read
    int numRead = -1;
 
    // the buffer to store text
    char data[MSG_SIZE];
 
    // the structures representing the server and client
    // addresses respectively
    sockaddr_in serverAddr, cliAddr;
 
    // stores the size of the client's address
    socklen_t cliLen = sizeof(cliAddr);
 
    // make sure the user has provided the port number to listen on
    if(argc < 2)
    {
        cerr<<"\n** ERROR NOT ENOUGH ARGS!\n"
            <<"USAGE: "<<argv[0]<<" <SERVER PORT #>\n\n";
        exit(1);
    }
 
    // get the port number
    port = atoi(argv[1]);
 
    // make sure that the port is within a valid range
    if(port < 0 || port > 65535)
    {
        cerr<<"Invalid port number\n";
        exit(1);
    }
 
    // create a socket that uses
    // IPV4 addressing scheme (AF_INET),
    // Supports reliable data transfer (SOCK_STREAM),
    // and choose the default protocol that provides
    // reliable service (i.e. 0); usually TCP
    if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket");
        exit(1);
    }
 
    // set the structure to all zeros
    memset(&serverAddr, 0, sizeof(serverAddr));
 
    // convert the port number to network representation
    serverAddr.sin_port = htons(port);
 
    // set the server family
    serverAddr.sin_family = AF_INET;
 
    // retrieve packets without having to know your IP address,
    // and retrieve packets from all network interfaces if the
    // machine has multiple ones
    serverAddr.sin_addr.s_addr = htonl(INADDR_ANY);
 
    // associate the address with the socket
    if(bind(listenfd, (sockaddr *) &serverAddr, sizeof(serverAddr)) < 0)
    {
        perror("bind");
        exit(1);
    }
 
    // listen for connections on socket listenfd.
    // allow no more than 100 pending clients.
    if(listen(listenfd, 100) < 0)
    {
        perror("listen");
        exit(1);
    }
 
    cerr<<"\nServer started!\n";
 
    // wait forever for connections to come
    while(true)
    {
        cerr<<"\nWaiting for someone to connect..\n";
 
        // a structure to store the client address
        if((connfd = accept(listenfd, (sockaddr *)&cliAddr, &cliLen)) < 0)
        {
            perror("accept");
            exit(1);
        }
 
        // receive whatever the client sends
        if((numRead = read(connfd, data, sizeof(data))) < 0)
        {
            perror("read");
            exit(1);
        }
 
        // NULL terminate the received string
        data[numRead] = '\0';
 
        cerr<<"\nRECEIVED: '"<<data<<"' from the client\n";
        //cerr<<"Bytes read: "<<numRead<<endl;
 
        // set the array to all zeros
        memset(&data, 0, sizeof(data));
 
        // retrieve the time
        time_t rawtime;
        time(&rawtime);
        struct tm* timeinfo;
        timeinfo = localtime(&rawtime);
        strftime(data, sizeof(data),"%a, %b %d %Y, %I:%M:%S %p", timeinfo);
 
        cerr<<"\nSENDING: '"<<data<<"' to the client\n";
 
        // send the client a message
        if(write(connfd, data, strlen(data)+1) < 0)
        {
            perror("write");
            exit(1);
        }
 
        // close the socket
        close(connfd);
    }
 
    return 0;
}// http://programmingnotes.org/

=== 2. CLIENT ===





		
		
			IPC Networking - TCP Client
			
C++
			
			// ============================================================================
//   Author: Kenneth Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ClientTCP.cpp
//   Description: This program implements a simple network application in
//     which a client sends text to a server and the server replies back to the
//     client. This is the client program, and has the following functionality:
//       1. Establish a connection to the server.
//       2. Send text to the server.
//       3. Recieve text from the server.
//       4. Close the connection and exit.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <ctime>
#include <cstdlib>
#include <cstring>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;

// Compile & Run
// g++ ClientTCP.cpp -o ClientTCP
// ./ClientTCP 127.0.0.1 1234

// the maximum size for sending/receiving text
const int MSG_SIZE = 100;

int main(int argc, char* argv[])
{
    // declare variables
    // the port number
    int port = -1;

    // the file descriptor representing the connection to the client
    int connfd = -1;

    // the buffer to store text
    char data[MSG_SIZE] = "Server, what time is it?";

    // the number of bytes read
    int numRead = -1;

    // the structures representing the server address
    sockaddr_in serverAddr;

    // stores the size of the client's address
    socklen_t servLen = sizeof(serverAddr);

    // make sure the user has provided the port number to listen on
    if(argc < 3)
    {
        cerr<<"\n** ERROR NOT ENOUGH ARGS!\n"
            <<"USAGE: "<<argv[0]<<" <SERVER IP> <SERVER PORT #>\n\n";
        exit(1);
    }

    // get the port number
    port = atoi(argv[2]);

    // make sure that the port is within a valid range
    if(port < 0 || port > 65535)
    {
        cerr<<"Invalid port number\n";
        exit(1);
    }

    // connect to the server
    if((connfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket");
        exit(1);
    }

    // set the structure to all zeros
    memset(&serverAddr, 0, sizeof(serverAddr));

    // set the server family
    serverAddr.sin_family = AF_INET;

    // convert the port number to network representation
    serverAddr.sin_port = htons(port);

    // convert the IP from the presentation format (i.e. string)
    // to the format in the serverAddr structure.
    if(!inet_pton(AF_INET, argv[1], &serverAddr.sin_addr))
    {
        perror("inet_pton");
        exit(1);
    }

    // connect to the server. This call will return a socket used
    // used for communications between the server and the client.
    if(connect(connfd, (sockaddr*)&serverAddr, sizeof(sockaddr)) < 0)
    {
        perror("connect");
        exit(1);
    }

    cerr<<"\nSENDING: '"<<data<<"' to the server\n";

    // send the server a message
    if(write(connfd, data, strlen(data)+1) < 0)
    {
        perror("write");
        exit(1);
    }

    // receive whatever the server sends
    if((numRead = read(connfd, data, sizeof(data))) < 0)
    {
        perror("read");
        exit(1);
    }

    // NULL terminate the received string
    data[numRead] = '\0';

    cerr<<"\nRECEIVED: '"<<data<<"' from the server\n";
    //cerr<<"Bytes read: "<<numRead<<endl;

    // close the connection socket
    close(connfd);

    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author: Kenneth Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ClientTCP.cpp
//   Description: This program implements a simple network application in
//     which a client sends text to a server and the server replies back to the
//     client. This is the client program, and has the following functionality:
//       1. Establish a connection to the server.
//       2. Send text to the server.
//       3. Recieve text from the server.
//       4. Close the connection and exit.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <ctime>
#include <cstdlib>
#include <cstring>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;
 
// Compile & Run
// g++ ClientTCP.cpp -o ClientTCP
// ./ClientTCP 127.0.0.1 1234
 
// the maximum size for sending/receiving text
const int MSG_SIZE = 100;
 
int main(int argc, char* argv[])
{
    // declare variables
    // the port number
    int port = -1;
 
    // the file descriptor representing the connection to the client
    int connfd = -1;
 
    // the buffer to store text
    char data[MSG_SIZE] = "Server, what time is it?";
 
    // the number of bytes read
    int numRead = -1;
 
    // the structures representing the server address
    sockaddr_in serverAddr;
 
    // stores the size of the client's address
    socklen_t servLen = sizeof(serverAddr);
 
    // make sure the user has provided the port number to listen on
    if(argc < 3)
    {
        cerr<<"\n** ERROR NOT ENOUGH ARGS!\n"
            <<"USAGE: "<<argv[0]<<" <SERVER IP> <SERVER PORT #>\n\n";
        exit(1);
    }
 
    // get the port number
    port = atoi(argv[2]);
 
    // make sure that the port is within a valid range
    if(port < 0 || port > 65535)
    {
        cerr<<"Invalid port number\n";
        exit(1);
    }
 
    // connect to the server
    if((connfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        perror("socket");
        exit(1);
    }
 
    // set the structure to all zeros
    memset(&serverAddr, 0, sizeof(serverAddr));
 
    // set the server family
    serverAddr.sin_family = AF_INET;
 
    // convert the port number to network representation
    serverAddr.sin_port = htons(port);
 
    // convert the IP from the presentation format (i.e. string)
    // to the format in the serverAddr structure.
    if(!inet_pton(AF_INET, argv[1], &serverAddr.sin_addr))
    {
        perror("inet_pton");
        exit(1);
    }
 
    // connect to the server. This call will return a socket used
    // used for communications between the server and the client.
    if(connect(connfd, (sockaddr*)&serverAddr, sizeof(sockaddr)) < 0)
    {
        perror("connect");
        exit(1);
    }
 
    cerr<<"\nSENDING: '"<<data<<"' to the server\n";
 
    // send the server a message
    if(write(connfd, data, strlen(data)+1) < 0)
    {
        perror("write");
        exit(1);
    }
 
    // receive whatever the server sends
    if((numRead = read(connfd, data, sizeof(data))) < 0)
    {
        perror("read");
        exit(1);
    }
 
    // NULL terminate the received string
    data[numRead] = '\0';
 
    cerr<<"\nRECEIVED: '"<<data<<"' from the server\n";
    //cerr<<"Bytes read: "<<numRead<<endl;
 
    // close the connection socket
    close(connfd);
 
    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.

The following is sample output.

SERVER OUTPUT:

Server started!
Waiting for someone to connect.. RECEIVED: "Server, what time is it?" from the client
SENDING: "Wed, Jan 08 2014, 07:51:53 PM" to the client

CLIENT OUTPUT:

SENDING: "Server, what time is it?" to the server
RECEIVED: "Wed, Jan 08 2014, 07:51:53 PM" from the server

C++ || Snippet – How To Send Text Over A Network Using A UDP Connection

January 08, 2014 admin No comments

The following is sample code which demonstrates the use of the “socket“, “bind“, “recvfrom“, and “sendto” function calls for interprocess communication over a network on Unix based systems.

Click here to examine the TCP version.

Note: The server program must be ran before the client program!

=== 1. SERVER ===





		
		
			IPC Networking - UDP Server
			
C++
			
			// ============================================================================
//   Author: K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ServerUDP.cpp
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the server program, and has the following functionality:
//       1. Listen for incoming connections on a specified port.
//       2. When a client connects, text is received from the client.
//       3. Text is sent back to the client from the server.
//       4. Go back to waiting for more connections.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <sys/socket.h>
#include <netinet/in.h>
using namespace std;

// Compile & Run
// g++ ServerUDP.cpp -o ServerUDP
// ./ServerUDP 1234

// the maximum size for sending/receiving text
const int MSG_SIZE = 100;

int main(int argc, char* argv[])
{
    // declare variables
    // to store the port number
    int port = -1;

    // to store the socket file descriptor
    int socketfd = -1;

    // the address structures for the server and the client
    sockaddr_in servaddr, cliaddr;

    // the size of sockaddr_in structure
    socklen_t sockaddr_in_len = 0;

    // the number of bytes received and sent
    int numRead = -1, numSent = -1;	
		
    // the buffer to store the string to send/receive
    char data[MSG_SIZE];

    // check the command line
    if(argc < 2)
    {
	    cerr<<"n** ERROR NOT ENOUGH ARGS!n"
	        <<"USAGE: "<<argv[0]<<" <SERVER PORT #>n";
	    exit(1);
    }
	
    // convert the port number to an integer
    port = atoi(argv[1]);

    // make sure the port range is valid
    if(port < 0 || port > 65535)	
    {
	    cerr<<"nInvalid port numbern";
	    exit(1);
    } 	
	
    // create a UDP socket
    if((socketfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
	    perror("socket");
	    exit(1);
    }	
	
    // clear the structure for the server address
    memset(&servaddr, 0, sizeof(servaddr));

    // populate the server address structure
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(port);

    // bind the socket to the port
    if(bind(socketfd,(sockaddr *)&servaddr, sizeof(servaddr)) < 0)
    {
	    perror("bind");
	    exit(1);
    }

    cerr<<"nServer started!n";
    
    // keep receiving forever
    while(true)
    {
        cerr<<"nWaiting for someone to connect..n";
            
        // get the size of the client address data structure
        sockaddr_in_len = sizeof(cliaddr);	

        // get something from the client; Will block until the client sends. 
        if((numRead = recvfrom(socketfd, data, sizeof(data), 0, 
            (sockaddr *)&cliaddr, &sockaddr_in_len)) < 0)
        {
            perror("recvfrom");
            exit(1);
        }	

        cerr<<"nRECEIVED: ""<<data<<"" from the clientn";
        //cerr<<"Bytes read: "<<numRead<<endl;          

        // set the array to all zeros 
        memset(&data, 0, sizeof(data));	

        // retrieve the time 
        time_t rawtime;
        time(&rawtime);
        struct tm* timeinfo;
        timeinfo = localtime(&rawtime);                	    	    
        strftime(data, sizeof(data),"%a, %b %d %Y, %I:%M:%S %p", timeinfo);
                
        cerr<<"nSENDING: ""<<data<<"" to the clientn";	

        // send the time to the client
        if((numSent = sendto(socketfd, data, strlen(data)+1, 0,
            (sockaddr *)&cliaddr,sizeof(cliaddr))) < 0)
        {
            perror("sendto");
            exit(1);
        }
    }

    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author: K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ServerUDP.cpp
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the server program, and has the following functionality:
//       1. Listen for incoming connections on a specified port.
//       2. When a client connects, text is received from the client.
//       3. Text is sent back to the client from the server.
//       4. Go back to waiting for more connections.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <sys/socket.h>
#include <netinet/in.h>
using namespace std;
 
// Compile & Run
// g++ ServerUDP.cpp -o ServerUDP
// ./ServerUDP 1234
 
// the maximum size for sending/receiving text
const int MSG_SIZE = 100;
 
int main(int argc, char* argv[])
{
    // declare variables
    // to store the port number
    int port = -1;
 
    // to store the socket file descriptor
    int socketfd = -1;
 
    // the address structures for the server and the client
    sockaddr_in servaddr, cliaddr;
 
    // the size of sockaddr_in structure
    socklen_t sockaddr_in_len = 0;
 
    // the number of bytes received and sent
    int numRead = -1, numSent = -1;	
		
    // the buffer to store the string to send/receive
    char data[MSG_SIZE];
 
    // check the command line
    if(argc < 2)
    {
	    cerr<<"n** ERROR NOT ENOUGH ARGS!n"
	        <<"USAGE: "<<argv[0]<<" <SERVER PORT #>n";
	    exit(1);
    }
	
    // convert the port number to an integer
    port = atoi(argv[1]);
 
    // make sure the port range is valid
    if(port < 0 || port > 65535)	
    {
	    cerr<<"nInvalid port numbern";
	    exit(1);
    } 	
	
    // create a UDP socket
    if((socketfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
	    perror("socket");
	    exit(1);
    }	
	
    // clear the structure for the server address
    memset(&servaddr, 0, sizeof(servaddr));
 
    // populate the server address structure
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(port);
 
    // bind the socket to the port
    if(bind(socketfd,(sockaddr *)&servaddr, sizeof(servaddr)) < 0)
    {
	    perror("bind");
	    exit(1);
    }
 
    cerr<<"nServer started!n";
    
    // keep receiving forever
    while(true)
    {
        cerr<<"nWaiting for someone to connect..n";
            
        // get the size of the client address data structure
        sockaddr_in_len = sizeof(cliaddr);	
 
        // get something from the client; Will block until the client sends. 
        if((numRead = recvfrom(socketfd, data, sizeof(data), 0, 
            (sockaddr *)&cliaddr, &sockaddr_in_len)) < 0)
        {
            perror("recvfrom");
            exit(1);
        }	
 
        cerr<<"nRECEIVED: ""<<data<<"" from the clientn";
        //cerr<<"Bytes read: "<<numRead<<endl;          
 
        // set the array to all zeros 
        memset(&data, 0, sizeof(data));	
 
        // retrieve the time 
        time_t rawtime;
        time(&rawtime);
        struct tm* timeinfo;
        timeinfo = localtime(&rawtime);                	    	    
        strftime(data, sizeof(data),"%a, %b %d %Y, %I:%M:%S %p", timeinfo);
                
        cerr<<"nSENDING: ""<<data<<"" to the clientn";	
 
        // send the time to the client
        if((numSent = sendto(socketfd, data, strlen(data)+1, 0,
            (sockaddr *)&cliaddr,sizeof(cliaddr))) < 0)
        {
            perror("sendto");
            exit(1);
        }
    }
 
    return 0;
}// http://programmingnotes.org/

=== 2. CLIENT ===





		
		
			IPC Networking - UDP Client
			
C++
			
			// ============================================================================
//   Author:  K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ClientUDP.cpp
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the client program, and has the following functionality:
//       1. Send text to the server on a specified port.
//       2. Recieve text from the server and exit.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;

// Compile & Run
// g++ ClientUDP.cpp -o ClientUDP
// ./ClientUDP 127.0.0.1 1234

// the maximum size for sending/receiving text
const int MSG_SIZE = 100;

int main(int argc, char* argv[])
{
    // declare variables
    // to store the port number
    int port = -1;

    // to store the socket file descriptor
    int socketfd = -1;

    // the address structures for the server and the client
    sockaddr_in servaddr, cliaddr;

    // the size of sockaddr_in structure
    socklen_t sockaddr_in_len = 0;

    // the number of bytes received and sent
    int numRead = -1, numSent = -1;	
		
    // the buffer to store the string to send/receive
    char data[MSG_SIZE] = "Server, what time is it?";

    // check the command line
    if(argc < 3)
    {
	    cerr<<"n** ERROR NOT ENOUGH ARGS!n"
	        <<"USAGE: "<<argv[0]<<" <SERVER IP> <SERVER PORT #>n";
	    exit(1);
    }
	
    // convert the port number to an integer
    port = atoi(argv[2]);

    // make sure the port range is valid
    if(port < 0 || port > 65535)	
    {
	    cerr<<"nInvalid port numbern";
	    exit(1);
    } 	
	
    // create a UDP socket
    if((socketfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
	    perror("socket");
	    exit(1);
    }

    // clear the structure for the server address
    memset(&servaddr, 0, sizeof(servaddr));

    // populate the server address structure
    servaddr.sin_family = AF_INET;
	
    // initialize the IP address of the server
    if(!inet_pton(AF_INET, argv[1], &servaddr.sin_addr.s_addr))
    {
	    perror("inet_pton");
	    exit(1);
    }

    // set the port
    servaddr.sin_port = htons(port);

    // get the size of the client address data structure
    sockaddr_in_len = sizeof(cliaddr);
    
    cerr<<"nSENDING: ""<<data<<"" to the servern";

    // send the time to the client
    if((numSent = sendto(socketfd, data, strlen(data)+1, 0,
				    (sockaddr *)&servaddr, sizeof(servaddr))) < 0)
    {
	    perror("sendto");
	    exit(1);
    }

    // get something from the client; Will block until the client sends. 
    if((numRead = recvfrom(socketfd, data, sizeof(data), 0, 
				    (sockaddr *)&cliaddr, &sockaddr_in_len)) < 0)
    {
	    perror("recvfrom");
	    exit(1);
    }

    // NULL terminate the received string 
    data[numRead] = '�';
	
    cerr<<"nRECEIVED: ""<<data<<"" from the servern"; 
    //cerr<<"Bytes read: "<<numRead<<endl;

    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author:  K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: ClientUDP.cpp
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the client program, and has the following functionality:
//       1. Send text to the server on a specified port.
//       2. Recieve text from the server and exit.
// ============================================================================
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;
 
// Compile & Run
// g++ ClientUDP.cpp -o ClientUDP
// ./ClientUDP 127.0.0.1 1234
 
// the maximum size for sending/receiving text
const int MSG_SIZE = 100;
 
int main(int argc, char* argv[])
{
    // declare variables
    // to store the port number
    int port = -1;
 
    // to store the socket file descriptor
    int socketfd = -1;
 
    // the address structures for the server and the client
    sockaddr_in servaddr, cliaddr;
 
    // the size of sockaddr_in structure
    socklen_t sockaddr_in_len = 0;
 
    // the number of bytes received and sent
    int numRead = -1, numSent = -1;	
		
    // the buffer to store the string to send/receive
    char data[MSG_SIZE] = "Server, what time is it?";
 
    // check the command line
    if(argc < 3)
    {
	    cerr<<"n** ERROR NOT ENOUGH ARGS!n"
	        <<"USAGE: "<<argv[0]<<" <SERVER IP> <SERVER PORT #>n";
	    exit(1);
    }
	
    // convert the port number to an integer
    port = atoi(argv[2]);
 
    // make sure the port range is valid
    if(port < 0 || port > 65535)	
    {
	    cerr<<"nInvalid port numbern";
	    exit(1);
    } 	
	
    // create a UDP socket
    if((socketfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    {
	    perror("socket");
	    exit(1);
    }
 
    // clear the structure for the server address
    memset(&servaddr, 0, sizeof(servaddr));
 
    // populate the server address structure
    servaddr.sin_family = AF_INET;
	
    // initialize the IP address of the server
    if(!inet_pton(AF_INET, argv[1], &servaddr.sin_addr.s_addr))
    {
	    perror("inet_pton");
	    exit(1);
    }
 
    // set the port
    servaddr.sin_port = htons(port);
 
    // get the size of the client address data structure
    sockaddr_in_len = sizeof(cliaddr);
    
    cerr<<"nSENDING: ""<<data<<"" to the servern";
 
    // send the time to the client
    if((numSent = sendto(socketfd, data, strlen(data)+1, 0,
				    (sockaddr *)&servaddr, sizeof(servaddr))) < 0)
    {
	    perror("sendto");
	    exit(1);
    }
 
    // get something from the client; Will block until the client sends. 
    if((numRead = recvfrom(socketfd, data, sizeof(data), 0, 
				    (sockaddr *)&cliaddr, &sockaddr_in_len)) < 0)
    {
	    perror("recvfrom");
	    exit(1);
    }
 
    // NULL terminate the received string 
    data[numRead] = '';
	
    cerr<<"nRECEIVED: ""<<data<<"" from the servern"; 
    //cerr<<"Bytes read: "<<numRead<<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.

The following is sample output.

SERVER OUTPUT:

Server started!
Waiting for someone to connect.. RECEIVED: "Server, what time is it?" from the client
SENDING: "Wed, Jan 08 2014, 11:47:12 PM" to the client

CLIENT OUTPUT:

SENDING: "Server, what time is it?" to the server
RECEIVED: "Wed, Jan 08 2014, 11:47:12 PM" from the server

Java || Snippet – How To Send Text Over A Network Using Socket

January 08, 2014 admin No comments

The following is sample code which demonstrates the use of the “socket” function call for interprocess communication over a network.

The following example demonstrates a simple network application in which a client sends text to a server, and the server replies (sends text) back to the client.

Note: The server program must be ran before the client program!

=== 1. SERVER ===





		
		
			IPC Networking - Server
			
Java
			
			// ============================================================================
//   Author: K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: Server.java
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the server program, and has the following functionality:
//       1. Listen for incoming connections on a specified port.
//       2. When a client tries to connect, the connection is accepted.
//       3. When a connection is created, text is received from the client.
//       4. Text is sent back to the client from the server.
//       5. Close the connection and go back to waiting for more connections.
// ============================================================================
import java.io.*;
import java.net.*;
import java.util.Date;

// Compile & Run
// javac Server.java
// java Server 1234

class Server
{
    // the port on which to listen 
    protected int listenPort;

    // the initialization constructor		 
    public Server(int port)
    {
	    // save the listening port 
	    listenPort = port;
    }// end of Server

    // executes the main server loop		 
    public void mainServerLoop() throws Exception
    { 
	    // create a listening socket in the specified port.	     
	    ServerSocket listenSock = new ServerSocket(this.listenPort);

	    // keep servicing the clients 
	    while(true)
	    {
		    System.out.println("nWaiting for someone to connect..");
		    
		    // accept the incoming connection from the client 
		    Socket communicationSocket = listenSock.accept();

		    // the client-to-server stream 
		    BufferedReader inFromClient =
			    new BufferedReader(new InputStreamReader(
			    communicationSocket.getInputStream()));

		    // the server-to-client stream 
		    DataOutputStream outToClient = 
			    new DataOutputStream(communicationSocket.getOutputStream());

		    // display misc. IPC information
		    System.out.println("n(SRCIP=" + communicationSocket.getInetAddress()+ 
		    ", SRCPORT="+communicationSocket.getPort() + ") "+"(DESTIP="+ 
		    communicationSocket.getLocalAddress()+", DESTPORT="+
                 	 communicationSocket.getLocalPort()+")");
                 	 
		    // receive a string from the client 
		    String clientMsg = inFromClient.readLine();
		    System.out.println("nRECEIVED: ""+clientMsg+"" from the client");
		
		    // instantiate a date class: used for obtaining the current time
		    Date date = new Date();

		    // send the current time and date to the client 
		    System.out.println("nSENDING: ""+date.toString()+"" to the client");
		    outToClient.writeBytes(date.toString());

		    // close the connection to the client 
		    communicationSocket.close();
	    }	
    }// end of mainServerLoop		

    public static void main(String[] args)
    {
	    // make sure the port number is provided 
	    if(args.length != 1)
	    {
		    System.out.println("USAGE: java Server <SERVER PORT #>");
	    }
	    else
	    {
		    // create an instance of the server class 
		    Server server = new Server(Integer.parseInt(args[0]));
		
		    try
		    {
			    // start receiving client connections 
			    System.out.println("nServer started!");
			    server.mainServerLoop();
		    }
		    catch(Exception e) { e.printStackTrace(); }
	    }
    }// end of main
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author: K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: Server.java
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the server program, and has the following functionality:
//       1. Listen for incoming connections on a specified port.
//       2. When a client tries to connect, the connection is accepted.
//       3. When a connection is created, text is received from the client.
//       4. Text is sent back to the client from the server.
//       5. Close the connection and go back to waiting for more connections.
// ============================================================================
import java.io.*;
import java.net.*;
import java.util.Date;
 
// Compile & Run
// javac Server.java
// java Server 1234
 
class Server
{
    // the port on which to listen 
    protected int listenPort;
 
    // the initialization constructor		 
    public Server(int port)
    {
	    // save the listening port 
	    listenPort = port;
    }// end of Server
 
    // executes the main server loop		 
    public void mainServerLoop() throws Exception
    { 
	    // create a listening socket in the specified port.	     
	    ServerSocket listenSock = new ServerSocket(this.listenPort);
 
	    // keep servicing the clients 
	    while(true)
	    {
		    System.out.println("nWaiting for someone to connect..");
		    
		    // accept the incoming connection from the client 
		    Socket communicationSocket = listenSock.accept();
 
		    // the client-to-server stream 
		    BufferedReader inFromClient =
			    new BufferedReader(new InputStreamReader(
			    communicationSocket.getInputStream()));
 
		    // the server-to-client stream 
		    DataOutputStream outToClient = 
			    new DataOutputStream(communicationSocket.getOutputStream());
 
		    // display misc. IPC information
		    System.out.println("n(SRCIP=" + communicationSocket.getInetAddress()+ 
		    ", SRCPORT="+communicationSocket.getPort() + ") "+"(DESTIP="+ 
		    communicationSocket.getLocalAddress()+", DESTPORT="+
                 	 communicationSocket.getLocalPort()+")");
                 	 
		    // receive a string from the client 
		    String clientMsg = inFromClient.readLine();
		    System.out.println("nRECEIVED: ""+clientMsg+"" from the client");
		
		    // instantiate a date class: used for obtaining the current time
		    Date date = new Date();
 
		    // send the current time and date to the client 
		    System.out.println("nSENDING: ""+date.toString()+"" to the client");
		    outToClient.writeBytes(date.toString());
 
		    // close the connection to the client 
		    communicationSocket.close();
	    }	
    }// end of mainServerLoop		
 
    public static void main(String[] args)
    {
	    // make sure the port number is provided 
	    if(args.length != 1)
	    {
		    System.out.println("USAGE: java Server <SERVER PORT #>");
	    }
	    else
	    {
		    // create an instance of the server class 
		    Server server = new Server(Integer.parseInt(args[0]));
		
		    try
		    {
			    // start receiving client connections 
			    System.out.println("nServer started!");
			    server.mainServerLoop();
		    }
		    catch(Exception e) { e.printStackTrace(); }
	    }
    }// end of main
}// http://programmingnotes.org/

=== 2. CLIENT ===





		
		
			IPC Networking - Client
			
Java
			
			// ============================================================================
//   Author: K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: Client.java
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the client program, and has the following functionality:
//       1. Establish a connection to the server.
//       2. Send text to the server.
//       3. Recieve text from the server.
//       4. Close the connection and exit.
// ============================================================================
import java.io.*;
import java.net.*;

// Compile & Run
// javac Client.java
// java Client localhost 1234

class Client
{
	// the server IP address  
	protected String svrIpAddr;
	
	// the server port number  
	protected int svrPort;
	
	/* the initialization constructor
	 * @param ipAddr - the IP address of the server
	 * @param port - the port on which the server is listening
	 */
	public Client(String ipAddr, int port)
	{
		// save the server's IP address and port number  
		svrIpAddr = ipAddr;
		svrPort = port;
	}// end of Client
	
	// connects to the server 	  
	public void connectToServer() throws Exception
	{
		// the message to send to the server  
		String msgForServer = "Server, what time is it?";
		
		// the string to store the date and time to be received from the server  
		String dateAndTime = null;
		
		// create a socket and use it for connecting to the server   
  		Socket clientSocket = new Socket(svrIpAddr, svrPort);
		
		// the client-to-server stream  
		DataOutputStream outToServer = 
				new DataOutputStream(clientSocket.getOutputStream());

		// the server-to-client stream  
		BufferedReader inFromServer = 
			new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
		
		// write the string to the server 
		System.out.println("nSENDING: ""+msgForServer+"" to the servern"); 	
		outToServer.writeBytes(msgForServer+"n");
		
		// get the date and time from the server  
  		dateAndTime = inFromServer.readLine();
		
		// print the date and time received from the server  
		System.out.println("RECEIVED: ""+dateAndTime+"" from the servern");
		
		// close the socket  
		clientSocket.close();
	}// end of connectToServer
	
	public static void main(String args[])
	{
		// check the command line arguments  
		if(args.length < 2)
		{
			System.err.println("n** ERROR NOT ENOUGH ARGS!n"
			    +"USAGE: Client <SERVER IP> <SERVER PORT #>n");
		}
		else
		{			
			// instantiate the client class  
			Client client = new Client(args[0], Integer.parseInt(args[1]));
			
			try
			{
				// connect to the server  
				client.connectToServer();	
			}
			catch(Exception e) { e.printStackTrace(); }
		}
	}// end of main
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//   Author: K Perkins
//   Date:  Jan 8, 2014
//   Taken From: http://programmingnotes.org/
//   File: Client.java
//   Description: This program implements a simple network application in 
//     which a client sends text to a server and the server replies back to the
//     client. This is the client program, and has the following functionality:
//       1. Establish a connection to the server.
//       2. Send text to the server.
//       3. Recieve text from the server.
//       4. Close the connection and exit.
// ============================================================================
import java.io.*;
import java.net.*;
 
// Compile & Run
// javac Client.java
// java Client localhost 1234
 
class Client
{
	// the server IP address  
	protected String svrIpAddr;
	
	// the server port number  
	protected int svrPort;
	
	/* the initialization constructor
	 * @param ipAddr - the IP address of the server
	 * @param port - the port on which the server is listening
	 */
	public Client(String ipAddr, int port)
	{
		// save the server's IP address and port number  
		svrIpAddr = ipAddr;
		svrPort = port;
	}// end of Client
	
	// connects to the server 	  
	public void connectToServer() throws Exception
	{
		// the message to send to the server  
		String msgForServer = "Server, what time is it?";
		
		// the string to store the date and time to be received from the server  
		String dateAndTime = null;
		
		// create a socket and use it for connecting to the server   
  		Socket clientSocket = new Socket(svrIpAddr, svrPort);
		
		// the client-to-server stream  
		DataOutputStream outToServer = 
				new DataOutputStream(clientSocket.getOutputStream());
 
		// the server-to-client stream  
		BufferedReader inFromServer = 
			new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
		
		// write the string to the server 
		System.out.println("nSENDING: ""+msgForServer+"" to the servern"); 	
		outToServer.writeBytes(msgForServer+"n");
		
		// get the date and time from the server  
  		dateAndTime = inFromServer.readLine();
		
		// print the date and time received from the server  
		System.out.println("RECEIVED: ""+dateAndTime+"" from the servern");
		
		// close the socket  
		clientSocket.close();
	}// end of connectToServer
	
	public static void main(String args[])
	{
		// check the command line arguments  
		if(args.length < 2)
		{
			System.err.println("n** ERROR NOT ENOUGH ARGS!n"
			    +"USAGE: Client <SERVER IP> <SERVER PORT #>n");
		}
		else
		{			
			// instantiate the client class  
			Client client = new Client(args[0], Integer.parseInt(args[1]));
			
			try
			{
				// connect to the server  
				client.connectToServer();	
			}
			catch(Exception e) { e.printStackTrace(); }
		}
	}// end of 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.

SERVER OUTPUT:

Server started!
Waiting for someone to connect.. (SRCIP=/127.0.0.1, SRCPORT=46608) (DESTIP=/127.0.0.1, DESTPORT=1234) RECEIVED: "Server, what time is it?" from the client
SENDING: "Wed Jan 08 18:07:15 PST 2014" to the client

CLIENT OUTPUT:

SENDING: "Server, what time is it?" to the server
RECEIVED: "Wed Jan 08 18:07:15 PST 2014" from the server

Python || Snippet – How To Send Text Over A Network Using Socket, Send, & Recv

January 08, 2014 admin No comments

The following is sample code which demonstrates the use of the “socket“, “connect“, “send“, and “recv” function calls for interprocess communication over a network.

The following example demonstrates a simple network application in which a client sends text to a server, and the server replies (sends text) back to the client.

Note: The server program must be ran before the client program!

=== 1. SERVER ===





		
		
			IPC Networking - Server
			
Python
			
			# =============================================================================
#   Author: Kenneth Perkins
#   Date:  Jan 8, 2014
#   Taken From: http://programmingnotes.org/
#   File: Server.py
#   Description: This program implements a simple network application in
#     which a client sends text to a server and the server replies back to the
#     client. This is the server program, which has the following functionality:
#       1. Listen for incoming connections on a specified port.
#       2. When a client tries to connect, the connection is accepted.
#       3. When a connection is created, text is received from the client.
#       4. Text is sent back to the client from the server.
#       5. Close the connection and go back to waiting for more connections.
# =============================================================================
import socket, sys, datetime

# Run
# python3 Server.py 1234

# the client message size
MAX_MSG_LEN = 4096

def main(argc, argv):
    # check the command line arguments
    if(argc < 2):
        print("\n** ERROR NOT ENOUGH ARGS!\n"
            "USAGE: %s <SERVER PORT #>\n" %(argv[0]))
        sys.exit(1)

    # get the port number
    port = int(argv[1])

    # the backlog
    backlog = 100

    # create A TCP socket
    listenSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    # bind the socket to the port
    listenSocket.bind(("", port))

    # start listening for incoming connections
    listenSocket.listen(backlog)

    print("\nServer started!")

    # service clients forever
    while(True):
        print("\nWaiting for someone to connect..")

        # accept a connection from the client
        client, address = listenSocket.accept()

        # get the data from the client
        data = client.recv(MAX_MSG_LEN)
        print("\nRECEIVED: '%s' from the client" %(data.decode("UTF-8")))

        # make sure the data was successfully received
        if(data):
            # get the current date and time
            now = datetime.datetime.now()
            dateAndTime = now.strftime("%a, %b %d %Y, %I:%M:%S %p")

            # send the date and time to the client
            print("\nSENDING: '%s' to the client" %(dateAndTime))
            client.send(dateAndTime.encode("UTF-8"))

        # close the connection to the client
        client.close()

if __name__ == "__main__":
    main(len(sys.argv), sys.argv)
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#   Author: Kenneth Perkins
#   Date:  Jan 8, 2014
#   Taken From: http://programmingnotes.org/
#   File: Server.py
#   Description: This program implements a simple network application in
#     which a client sends text to a server and the server replies back to the
#     client. This is the server program, which has the following functionality:
#       1. Listen for incoming connections on a specified port.
#       2. When a client tries to connect, the connection is accepted.
#       3. When a connection is created, text is received from the client.
#       4. Text is sent back to the client from the server.
#       5. Close the connection and go back to waiting for more connections.
# =============================================================================
import socket, sys, datetime
 
# Run
# python3 Server.py 1234
 
# the client message size
MAX_MSG_LEN = 4096
 
def main(argc, argv):
    # check the command line arguments
    if(argc < 2):
        print("\n** ERROR NOT ENOUGH ARGS!\n"
            "USAGE: %s <SERVER PORT #>\n" %(argv[0]))
        sys.exit(1)
 
    # get the port number
    port = int(argv[1])
 
    # the backlog
    backlog = 100
 
    # create A TCP socket
    listenSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 
    # bind the socket to the port
    listenSocket.bind(("", port))
 
    # start listening for incoming connections
    listenSocket.listen(backlog)
 
    print("\nServer started!")
 
    # service clients forever
    while(True):
        print("\nWaiting for someone to connect..")
 
        # accept a connection from the client
        client, address = listenSocket.accept()
 
        # get the data from the client
        data = client.recv(MAX_MSG_LEN)
        print("\nRECEIVED: '%s' from the client" %(data.decode("UTF-8")))
 
        # make sure the data was successfully received
        if(data):
            # get the current date and time
            now = datetime.datetime.now()
            dateAndTime = now.strftime("%a, %b %d %Y, %I:%M:%S %p")
 
            # send the date and time to the client
            print("\nSENDING: '%s' to the client" %(dateAndTime))
            client.send(dateAndTime.encode("UTF-8"))
 
        # close the connection to the client
        client.close()
 
if __name__ == "__main__":
    main(len(sys.argv), sys.argv)
# http://programmingnotes.org/

=== 2. CLIENT ===





		
		
			IPC Networking - Client
			
Python
			
			# =============================================================================
#   Author: Kenneth Perkins
#   Date:  Jan 8, 2014
#   Taken From: http://programmingnotes.org/
#   File: Client.py
#   Description: This program implements a simple network application in
#     which a client sends text to a server and the server replies back to the
#     client. This is the client program, which has the following functionality:
#       1. Establish a connection to the server.
#       2. Send text to the server.
#       3. Recieve text from the server.
#       4. Close the connection and exit.
# =============================================================================
import socket, sys

# Run
# python3 Client.py localhost 1234

# the size of the message sent by server
MAX_MSG_LEN = 4096

def main(argc, argv):
    # check the command line arguments
    if(argc < 3):
        print("\n** ERROR NOT ENOUGH ARGS!\n"
            "USAGE: %s <SERVER IP> <SERVER PORT #>\n" %(argv[0]))
        sys.exit(1)

    # get the host name (or IP)
    host = argv[1]

    # get the server's port number
    port = int(argv[2])

    # the client socket
    clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    # connect to the server
    clientSocket.connect((host,port))

    # send a string to the server
    data = "Server, what time is it?"
    print("\nSENDING: '%s' to the server" %(data))
    clientSocket.send(data.encode("UTF-8"))

    # get the date from the server
    data = clientSocket.recv(MAX_MSG_LEN)
    print("\nRECEIVED: '%s' from the server\n" %(data.decode("UTF-8")))

    # close the connection to the server
    clientSocket.close()

if __name__ == "__main__":
    main(len(sys.argv), sys.argv)
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#   Author: Kenneth Perkins
#   Date:  Jan 8, 2014
#   Taken From: http://programmingnotes.org/
#   File: Client.py
#   Description: This program implements a simple network application in
#     which a client sends text to a server and the server replies back to the
#     client. This is the client program, which has the following functionality:
#       1. Establish a connection to the server.
#       2. Send text to the server.
#       3. Recieve text from the server.
#       4. Close the connection and exit.
# =============================================================================
import socket, sys
 
# Run
# python3 Client.py localhost 1234
 
# the size of the message sent by server
MAX_MSG_LEN = 4096
 
def main(argc, argv):
    # check the command line arguments
    if(argc < 3):
        print("\n** ERROR NOT ENOUGH ARGS!\n"
            "USAGE: %s <SERVER IP> <SERVER PORT #>\n" %(argv[0]))
        sys.exit(1)
 
    # get the host name (or IP)
    host = argv[1]
 
    # get the server's port number
    port = int(argv[2])
 
    # the client socket
    clientSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 
    # connect to the server
    clientSocket.connect((host,port))
 
    # send a string to the server
    data = "Server, what time is it?"
    print("\nSENDING: '%s' to the server" %(data))
    clientSocket.send(data.encode("UTF-8"))
 
    # get the date from the server
    data = clientSocket.recv(MAX_MSG_LEN)
    print("\nRECEIVED: '%s' from the server\n" %(data.decode("UTF-8")))
 
    # close the connection to the server
    clientSocket.close()
 
if __name__ == "__main__":
    main(len(sys.argv), sys.argv)
# 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.

SERVER OUTPUT:

Server started!
Waiting for someone to connect.. RECEIVED: "Server, what time is it?" from the client
SENDING: "Wed, Jan 08 2014, 04:02:13 PM" to the client

CLIENT OUTPUT:

SENDING: "Server, what time is it?" to the server
RECEIVED: "Wed, Jan 08 2014, 04:02:13 PM" from the server

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