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C++ || Simple Palindrome Checker Using A Stack & Queue Using C++

April 02, 2021 admin No comments

The following is a program which demonstrates how to use a stack and a queue to test for a palindrome using C++.

The program demonstrated on this page is an updated version of a previous program of the same type. This program is great practice for understanding how the two data structures work.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

Template Classes - What Are They? Stacks Queues LIFO - Last In First Out FIFO - First In First Out

1. Overview

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

2. Palindrome Checker





		
		
			Palindrome Checker Using Stack & Queue
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 22, 2012
//    Updated: Apr 2, 2021
//    Taken From: http://programmingnotes.org/
//    File:  palindrome.cpp
//    Description: Demonstrates a palindrome checker using a stack & queue
// ============================================================================
#include <iostream>
#include <cctype>
#include <string>
#include <queue>
#include <stack>

int main() {
    // Declare variables
    std::string text = "";
    bool isPalindrome = true;
    std::queue<char> queue;
    std::stack<char> stack;

    // Get data from user
    std::cout << "Enter in some text to see if its a palindrome: ";
    std::getline(std::cin, text);

    // Place the characters into the queue and stack for storage
    for (auto ch : text) {
        ch = std::toupper(ch);
        queue.push(ch);
        stack.push(ch);
    }

    // Determine if the string is a palindrome
    while (!queue.empty() && !stack.empty()) {
        if (queue.front() != stack.top()) {
            isPalindrome = false;
            break;
        }
        queue.pop();
        stack.pop();
    }

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

    std::cin.get();
    return 0;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 22, 2012
//    Updated: Apr 2, 2021
//    Taken From: http://programmingnotes.org/
//    File:  palindrome.cpp
//    Description: Demonstrates a palindrome checker using a stack & queue
// ============================================================================
#include <iostream>
#include <cctype>
#include <string>
#include <queue>
#include <stack>
 
int main() {
    // Declare variables
    std::string text = "";
    bool isPalindrome = true;
    std::queue<char> queue;
    std::stack<char> stack;
 
    // Get data from user
    std::cout << "Enter in some text to see if its a palindrome: ";
    std::getline(std::cin, text);
 
    // Place the characters into the queue and stack for storage
    for (auto ch : text) {
        ch = std::toupper(ch);
        queue.push(ch);
        stack.push(ch);
    }
 
    // Determine if the string is a palindrome
    while (!queue.empty() && !stack.empty()) {
        if (queue.front() != stack.top()) {
            isPalindrome = false;
            break;
        }
        queue.pop();
        stack.pop();
    }
 
    // Display results to the screen
    std::cout << "\n\n" << text;
    if (isPalindrome) {
        std::cout << " is a palindrome!\n";
    } else {
        std::cout << " is NOT a palindrome..\n";
    }
 
    std::cin.get();
    return 0;
}// http://programmingnotes.org/

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

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

Once compiled, you should get this as your output:

====== RUN 1 ======
Enter in some text to see if its a palindrome: StEP on No pETS StEP on No pETS is a palindrome! ====== RUN 2 ====== Enter in some text to see if its a palindrome: Hello World Hello World is NOT a palindrome.. ====== RUN 3 ====== Enter in some text to see if its a palindrome: Kenneth, Jennifer, Lynn, Sole
Kenneth, Jennifer, Lynn, Sole is NOT a palindrome..

C++ || Snippet – Custom Template Linked List Sample Code

July 26, 2012 admin 1 Comment

This page will consist of sample code for a singly linked list, which is loosely based on the built in C++ “List” library. Provided in the linked list class are the following functions:





		
		
			* PushFront - Adds new item to the front of the list (LIFO)

* PushBack - Adds new item to the back of the list (FIFO)

* PopFront - Returns & removes first item from the list

* PopBack - Returns & removes last item from the list

* Front - Returns (but does not delete) the first item from the list

* Back - Returns (but does not delete) the last item from the list

* Delete - Searches and deletes the requested item

* Display - Display all the current contents in the list

* Replace - Replaces existing item from the list with a new item
            If existing item cannot be found, the new item is added to the back of the list

* InsertBefore - Inserts new item before the existing item. 
                If existing item cannot be found, the new item is added to the back of the list

* InsertAfter - Inserts new item after the existing item. 
                If existing item cannot be found, the new item is added to the back of the list

* InsertInOrder - Inserts new item in numerical order, from lowest to highest

* Size - Return the current size of the list

* MakeEmpty - Initializes the list to an empty state 
			
				
					
				
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						* PushFront - Adds new item to the front of the list (LIFO)
 
* PushBack - Adds new item to the back of the list (FIFO)
 
* PopFront - Returns & removes first item from the list
 
* PopBack - Returns & removes last item from the list
 
* Front - Returns (but does not delete) the first item from the list
 
* Back - Returns (but does not delete) the last item from the list
 
* Delete - Searches and deletes the requested item
 
* Display - Display all the current contents in the list
 
* Replace - Replaces existing item from the list with a new item
            If existing item cannot be found, the new item is added to the back of the list
 
* InsertBefore - Inserts new item before the existing item. 
                If existing item cannot be found, the new item is added to the back of the list
 
* InsertAfter - Inserts new item after the existing item. 
                If existing item cannot be found, the new item is added to the back of the list
 
* InsertInOrder - Inserts new item in numerical order, from lowest to highest
 
* Size - Return the current size of the list
 
* MakeEmpty - Initializes the list to an empty state

From the following, the functions of interest to look out for are the “Delete, Display, Replace, InsertBefore, InsertAfter, and InsertInOrder” functions as they are typically used as programming assignments in many C++ Data structures courses to further demonstrate how linked lists operate.





		
		
			#include 'LinkedList.h'
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 26, 2012
//    Taken From: http://programmingnotes.org/
//    File:  LinkedList.h
//    Description: This is a class which implements various functions which
//          demonstrates the use of a Linked List. 
// ============================================================================
#include <iostream>

template <class ItemType>
class LinkedList
{
public:
    LinkedList();
        /*   Function: Constructor initializes list 
            Precondition: None
            Postcondition: Defines private variables */
    bool IsEmpty();
        /*   Function: Determines whether queue is empty
            Precondition: List has been created
            Postcondition: The function = true if the list is empty and the
                             function = false if list is not empty */
    void PushFront(ItemType item);
        /*   Function: Adds new item to the front of the list (LIFO)
            Precondition:  List has been created and is not full
            Postcondition: Item is in the list */
    void PushBack(ItemType item);
        /*   Function: Adds new item to the back of the list (FIFO)
            Precondition:  List has been created and is not full
            Postcondition: Item is in the list */
    ItemType PopFront();
        /*   Function: Returns & removes first item from the last
            Precondition: List has been initialized
            Postcondition: The first item in the list is removed */
    ItemType PopBack();
        /*   Function: Returns & removes last item from the list
            Precondition: List has been initialized
            Postcondition: The last item in the list is removed */
    ItemType Front();
        /*   Function: Returns (but does not delete) the first item from the list
            Precondition: List has been initialized
            Postcondition: The first item in the list is removed */
    ItemType Back();
        /*   Function: Returns (but does not delete) the last item from the list
            Precondition: List has been initialized
            Postcondition: The last item in the list is removed */
    void Delete(ItemType item);
        /*   Function: Searches and deletes the requested item
            Precondition:  List has been created and is not empty
            Postcondition: Item removed from the list */
    void Display();
        /*   Function: Display all the current contents in the list
            Precondition:  List has been created and is not empty
            Postcondition: List is displayed to the screen */
    void Replace(ItemType initial, ItemType replace);
        /*   Function: Replaces existing item from the list with a new item
            Precondition:  List has been created and is not empty
            Postcondition: Initial item is replaced with the new one */
    void InsertBefore(ItemType initial, ItemType newItem);
        /*   Function: Inserts new item before the existing item
            Precondition:  List has been created and is not empty
            Postcondition: New item is inserted before the existing item */
    void InsertAfter(ItemType initial, ItemType newItem);
        /*   Function: Inserts new item after the existing item
            Precondition:  List has been created and is not empty
            Postcondition: New item is inserted after the existing item */
    void InsertInOrder(ItemType item);  
        /*   Function: Inserts new item in numerical order, from lowest to highest
            Precondition:  List has been created and is not empty
            Postcondition: The list is sorted in numerical order */
    int Size();
        /*   Function: Return the current size of the list
            Precondition: List has been initialized
            Postcondition: The size of the list is returned */
    void MakeEmpty();
        /*   Function: Initializes the list to an empty state 
            Precondition: List has been created
            Postcondition: List no longer exists */
    ~LinkedList();
        /*   Function: Deletes all the items in the list
            Precondition: List has been declared
            Postcondition: List no longer exists */

private:
    struct node
    {
        ItemType info;
        node* next;
    };
    node* head; 
    int size;
};

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

template <class ItemType>
LinkedList<ItemType>::LinkedList()
{
    head = NULL;
    size = 0;
}// end of LinkedList

template <class ItemType>
bool LinkedList<ItemType>::IsEmpty()
{
    return (head==NULL);
}// end of IsEmpty

template <class ItemType>
void LinkedList<ItemType>::PushFront(ItemType item)
{
    // LIFO 
    node* temp = new node;
    temp-> info = item;
    temp-> next = head;
    head = temp;
    ++size;
}// end of PushFront

template <class ItemType>
void LinkedList<ItemType>::PushBack(ItemType item)
{
    // FIFO
    node* temp = new node;
    temp->info = item;
    temp->next = NULL;
    
    if(IsEmpty())
    {
        head=temp;
    }
    else
    {
        node* temp2 = head;        
        while(temp2->next!=NULL)
        {
            temp2=temp2->next;
        }
        temp2->next=temp;
    }
    ++size;
}// end of PushBack

template <class ItemType>
ItemType LinkedList<ItemType>::PopFront()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else
    {  
        ItemType item = head-> info;  
        node* temp = head;
        head = head-> next;
        delete temp;
        --size;
        return item;
    }
}// end of PopFront

template <class ItemType>
ItemType LinkedList<ItemType>::PopBack()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else if(size == 1)
    {
        ItemType item = PopFront();
        return item;
    }
    else
    {
        node* temp = head;
        ItemType item;
        while(temp->next != NULL)
        {
            if(temp->next->next==NULL)
            {
                node* temp2=temp->next;
                temp->next=temp->next->next;
                item = temp2-> info;
                delete temp2;
                break;
            }
            temp=temp->next;
        }
        --size;
        return item;
    }   
}// end of PopBack

template <class ItemType>
ItemType LinkedList<ItemType>::Front()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else
    { 
        return head-> info;
    }
}// end of Front

template <class ItemType>
ItemType LinkedList<ItemType>::Back() 
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else
    {
        node* temp = head; 
        while(temp->next != NULL)
        {
            temp = temp-> next;
        }
        ItemType item = temp-> info;
        return item;
    }   
}// end of Back

template <class ItemType>
void LinkedList<ItemType>::Delete(ItemType item)
{
    node* temp=head;
    if(IsEmpty())
    {
        return;
    }
    else if(temp->info==item)
    {
        head=head->next;
        delete temp;
        --size;
    }
    else
    {
        while(temp->next!=NULL)
        {
            if(temp->next->info==item)
            {
                node* temp2=temp->next;
                temp->next=temp->next->next;
                delete temp2;
                --size;
                break;
            }
            temp=temp->next;
        }
    }
}// end of Delete

template <class ItemType>
void LinkedList<ItemType>::Display()
{
    node* temp=head;
    while(temp!=NULL)
    {
        std::cout<<temp->info<<std::endl;
        temp=temp->next;
    }
}// end of Display

template <class ItemType>
void LinkedList<ItemType>::Replace(ItemType initial, ItemType replace)
{
    node* temp=head;
    if(IsEmpty())
    {
        PushFront(replace);
    }
    else if(temp->info==initial)
    {
        temp->info=replace;
    }
    else
    {        
        while(temp->next!=NULL)
        {
            if(temp->info==initial)
            {
                temp->info=replace;
                break;
            }
            temp=temp->next;
        }
        if(temp->next==NULL)
        {
            PushBack(replace);
        }
    }
}// end of Replace

template <class ItemType>
void LinkedList<ItemType>::InsertBefore(ItemType initial, ItemType newItem)
{
    node* temp=head;
    node* temp2=new node;
    temp2->info=initial;
    temp2->next=NULL;     
    
    if(IsEmpty())
    {
        PushFront(newItem);
    }
    else if(temp->info==initial)
    {
        temp->info=newItem; 
        temp2->next=temp->next;
        temp->next=temp2;
        ++size;
    }
    else
    {
        while(temp->next!=NULL)
        {
            if(temp->info==initial)
            {
                temp->info=newItem; 
                temp2->next=temp->next;
                temp->next=temp2;
                ++size;
                break;
            }
            temp=temp->next;           
        }
        if(temp->next==NULL)
        {
            PushBack(newItem);
        }
    }
}// end of InsertBefore

template <class ItemType>
void LinkedList<ItemType>::InsertAfter(ItemType initial, ItemType newItem)
{
    node* temp=head;
    node* temp2=new node;
    temp2->info=newItem;
    temp2->next=NULL;
    
    if(IsEmpty())
    {
        PushFront(newItem);
    }
    else if(temp->info==initial)
    {
        temp2->next=temp->next;
        temp->next=temp2;
        ++size;
    }
    else
    {   
        while(temp->next!=NULL)
        {
            if(temp->info==initial)
            {
                temp2->next=temp->next;
                temp->next=temp2;
                ++size;
                break;
            }
            temp=temp->next;
        }
        if(temp->next==NULL)
        {
            PushBack(newItem);
        }
    }
}// end of InsertAfter

template <class ItemType>
void LinkedList<ItemType>::InsertInOrder(ItemType item)
{
    if(IsEmpty())
    {
        PushFront(item);
    }
    else
    {
        node* temp=head;
        node* temp2=new node;
    
        if(item <=(temp->info))
        {  
            ItemType placeHolder=temp->info;
            temp2->info=placeHolder;
            temp->info=item;
            temp2->next=temp->next;
            temp->next=temp2;
            ++size;
        } 
        else
        {
            while(temp->next!=NULL)
            {       
                if(((temp->info) <= item) && (item <= (temp->next->info)))
                {           
                    temp2->info=item;
                    temp2->next=temp->next;
                    temp->next=temp2;
                    ++size;
                    return;
                }
                temp=temp->next;
            }
            if(temp->next==NULL)
            {
                PushBack(item);
            }
        }
    }
}// end of InsertInOrder

template <class ItemType>
int LinkedList<ItemType>::Size()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    return size;
}// end of Size 

template <class ItemType>
void LinkedList<ItemType>::MakeEmpty()
{
    if(!IsEmpty())
    {
        std::cout << "\nDestroying nodes...\n";
        while(!IsEmpty())
        {
            node* temp = head;
            //std::cout << temp-> info << '\n';
            head = head-> next;
            delete temp;
        }
        size = 0;
    }
}// end of MakeEmpty

template <class ItemType>
LinkedList<ItemType>::~LinkedList()
{
    MakeEmpty();
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Jul 26, 2012
//    Taken From: http://programmingnotes.org/
//    File:  LinkedList.h
//    Description: This is a class which implements various functions which
//          demonstrates the use of a Linked List. 
// ============================================================================
#include <iostream>
 
template <class ItemType>
class LinkedList
{
public:
    LinkedList();
        /*   Function: Constructor initializes list 
            Precondition: None
            Postcondition: Defines private variables */
    bool IsEmpty();
        /*   Function: Determines whether queue is empty
            Precondition: List has been created
            Postcondition: The function = true if the list is empty and the
                             function = false if list is not empty */
    void PushFront(ItemType item);
        /*   Function: Adds new item to the front of the list (LIFO)
            Precondition:  List has been created and is not full
            Postcondition: Item is in the list */
    void PushBack(ItemType item);
        /*   Function: Adds new item to the back of the list (FIFO)
            Precondition:  List has been created and is not full
            Postcondition: Item is in the list */
    ItemType PopFront();
        /*   Function: Returns & removes first item from the last
            Precondition: List has been initialized
            Postcondition: The first item in the list is removed */
    ItemType PopBack();
        /*   Function: Returns & removes last item from the list
            Precondition: List has been initialized
            Postcondition: The last item in the list is removed */
    ItemType Front();
        /*   Function: Returns (but does not delete) the first item from the list
            Precondition: List has been initialized
            Postcondition: The first item in the list is removed */
    ItemType Back();
        /*   Function: Returns (but does not delete) the last item from the list
            Precondition: List has been initialized
            Postcondition: The last item in the list is removed */
    void Delete(ItemType item);
        /*   Function: Searches and deletes the requested item
            Precondition:  List has been created and is not empty
            Postcondition: Item removed from the list */
    void Display();
        /*   Function: Display all the current contents in the list
            Precondition:  List has been created and is not empty
            Postcondition: List is displayed to the screen */
    void Replace(ItemType initial, ItemType replace);
        /*   Function: Replaces existing item from the list with a new item
            Precondition:  List has been created and is not empty
            Postcondition: Initial item is replaced with the new one */
    void InsertBefore(ItemType initial, ItemType newItem);
        /*   Function: Inserts new item before the existing item
            Precondition:  List has been created and is not empty
            Postcondition: New item is inserted before the existing item */
    void InsertAfter(ItemType initial, ItemType newItem);
        /*   Function: Inserts new item after the existing item
            Precondition:  List has been created and is not empty
            Postcondition: New item is inserted after the existing item */
    void InsertInOrder(ItemType item);  
        /*   Function: Inserts new item in numerical order, from lowest to highest
            Precondition:  List has been created and is not empty
            Postcondition: The list is sorted in numerical order */
    int Size();
        /*   Function: Return the current size of the list
            Precondition: List has been initialized
            Postcondition: The size of the list is returned */
    void MakeEmpty();
        /*   Function: Initializes the list to an empty state 
            Precondition: List has been created
            Postcondition: List no longer exists */
    ~LinkedList();
        /*   Function: Deletes all the items in the list
            Precondition: List has been declared
            Postcondition: List no longer exists */
 
private:
    struct node
    {
        ItemType info;
        node* next;
    };
    node* head; 
    int size;
};
 
//=========================  Implementation  ================================//
 
template <class ItemType>
LinkedList<ItemType>::LinkedList()
{
    head = NULL;
    size = 0;
}// end of LinkedList
 
template <class ItemType>
bool LinkedList<ItemType>::IsEmpty()
{
    return (head==NULL);
}// end of IsEmpty
 
template <class ItemType>
void LinkedList<ItemType>::PushFront(ItemType item)
{
    // LIFO 
    node* temp = new node;
    temp-> info = item;
    temp-> next = head;
    head = temp;
    ++size;
}// end of PushFront
 
template <class ItemType>
void LinkedList<ItemType>::PushBack(ItemType item)
{
    // FIFO
    node* temp = new node;
    temp->info = item;
    temp->next = NULL;
    
    if(IsEmpty())
    {
        head=temp;
    }
    else
    {
        node* temp2 = head;        
        while(temp2->next!=NULL)
        {
            temp2=temp2->next;
        }
        temp2->next=temp;
    }
    ++size;
}// end of PushBack
 
template <class ItemType>
ItemType LinkedList<ItemType>::PopFront()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else
    {  
        ItemType item = head-> info;  
        node* temp = head;
        head = head-> next;
        delete temp;
        --size;
        return item;
    }
}// end of PopFront
 
template <class ItemType>
ItemType LinkedList<ItemType>::PopBack()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else if(size == 1)
    {
        ItemType item = PopFront();
        return item;
    }
    else
    {
        node* temp = head;
        ItemType item;
        while(temp->next != NULL)
        {
            if(temp->next->next==NULL)
            {
                node* temp2=temp->next;
                temp->next=temp->next->next;
                item = temp2-> info;
                delete temp2;
                break;
            }
            temp=temp->next;
        }
        --size;
        return item;
    }   
}// end of PopBack
 
template <class ItemType>
ItemType LinkedList<ItemType>::Front()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else
    { 
        return head-> info;
    }
}// end of Front
 
template <class ItemType>
ItemType LinkedList<ItemType>::Back() 
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    else
    {
        node* temp = head; 
        while(temp->next != NULL)
        {
            temp = temp-> next;
        }
        ItemType item = temp-> info;
        return item;
    }   
}// end of Back
 
template <class ItemType>
void LinkedList<ItemType>::Delete(ItemType item)
{
    node* temp=head;
    if(IsEmpty())
    {
        return;
    }
    else if(temp->info==item)
    {
        head=head->next;
        delete temp;
        --size;
    }
    else
    {
        while(temp->next!=NULL)
        {
            if(temp->next->info==item)
            {
                node* temp2=temp->next;
                temp->next=temp->next->next;
                delete temp2;
                --size;
                break;
            }
            temp=temp->next;
        }
    }
}// end of Delete
 
template <class ItemType>
void LinkedList<ItemType>::Display()
{
    node* temp=head;
    while(temp!=NULL)
    {
        std::cout<<temp->info<<std::endl;
        temp=temp->next;
    }
}// end of Display
 
template <class ItemType>
void LinkedList<ItemType>::Replace(ItemType initial, ItemType replace)
{
    node* temp=head;
    if(IsEmpty())
    {
        PushFront(replace);
    }
    else if(temp->info==initial)
    {
        temp->info=replace;
    }
    else
    {        
        while(temp->next!=NULL)
        {
            if(temp->info==initial)
            {
                temp->info=replace;
                break;
            }
            temp=temp->next;
        }
        if(temp->next==NULL)
        {
            PushBack(replace);
        }
    }
}// end of Replace
 
template <class ItemType>
void LinkedList<ItemType>::InsertBefore(ItemType initial, ItemType newItem)
{
    node* temp=head;
    node* temp2=new node;
    temp2->info=initial;
    temp2->next=NULL;     
    
    if(IsEmpty())
    {
        PushFront(newItem);
    }
    else if(temp->info==initial)
    {
        temp->info=newItem; 
        temp2->next=temp->next;
        temp->next=temp2;
        ++size;
    }
    else
    {
        while(temp->next!=NULL)
        {
            if(temp->info==initial)
            {
                temp->info=newItem; 
                temp2->next=temp->next;
                temp->next=temp2;
                ++size;
                break;
            }
            temp=temp->next;           
        }
        if(temp->next==NULL)
        {
            PushBack(newItem);
        }
    }
}// end of InsertBefore
 
template <class ItemType>
void LinkedList<ItemType>::InsertAfter(ItemType initial, ItemType newItem)
{
    node* temp=head;
    node* temp2=new node;
    temp2->info=newItem;
    temp2->next=NULL;
    
    if(IsEmpty())
    {
        PushFront(newItem);
    }
    else if(temp->info==initial)
    {
        temp2->next=temp->next;
        temp->next=temp2;
        ++size;
    }
    else
    {   
        while(temp->next!=NULL)
        {
            if(temp->info==initial)
            {
                temp2->next=temp->next;
                temp->next=temp2;
                ++size;
                break;
            }
            temp=temp->next;
        }
        if(temp->next==NULL)
        {
            PushBack(newItem);
        }
    }
}// end of InsertAfter
 
template <class ItemType>
void LinkedList<ItemType>::InsertInOrder(ItemType item)
{
    if(IsEmpty())
    {
        PushFront(item);
    }
    else
    {
        node* temp=head;
        node* temp2=new node;
    
        if(item <=(temp->info))
        {  
            ItemType placeHolder=temp->info;
            temp2->info=placeHolder;
            temp->info=item;
            temp2->next=temp->next;
            temp->next=temp2;
            ++size;
        } 
        else
        {
            while(temp->next!=NULL)
            {       
                if(((temp->info) <= item) && (item <= (temp->next->info)))
                {           
                    temp2->info=item;
                    temp2->next=temp->next;
                    temp->next=temp2;
                    ++size;
                    return;
                }
                temp=temp->next;
            }
            if(temp->next==NULL)
            {
                PushBack(item);
            }
        }
    }
}// end of InsertInOrder
 
template <class ItemType>
int LinkedList<ItemType>::Size()
{
    if(IsEmpty())
    {
        std::cout<<"\nLIST EMPTY\n";
    }
    return size;
}// end of Size 
 
template <class ItemType>
void LinkedList<ItemType>::MakeEmpty()
{
    if(!IsEmpty())
    {
        std::cout << "\nDestroying nodes...\n";
        while(!IsEmpty())
        {
            node* temp = head;
            //std::cout << temp-> info << '\n';
            head = head-> next;
            delete temp;
        }
        size = 0;
    }
}// end of MakeEmpty
 
template <class ItemType>
LinkedList<ItemType>::~LinkedList()
{
    MakeEmpty();
}// http://programmingnotes.org/

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

Use of the above template class is the same as its STL counterpart. Here is a sample program demonstrating its use.





		
		
			How To Use #include 'LinkedList.h'
			
C++
			
			#include <iostream>
#include <string>
#include "LinkedList.h"
using namespace std;

int main()
{
    // declare variables, using a string as
    // the item type for the class. 

    // NOTE: you can also use an int, float, double etc.
    // instead of a string
    LinkedList<string> list;

    // demontrate the "InOrder" function
    cout<<"** These are names of fruits sorted in order"
        <<" using the 'InsertInOrder()' function:\n\n";
    list.InsertInOrder("Tomato");
    list.InsertInOrder("Orange");
    list.InsertInOrder("Apple");
    list.InsertInOrder("Plum");
    list.Display();

    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";

    // demonstrate the "Delete" function
    cout<<"\n** Here is the same list with the word 'Plum' deleted"
        << "\nusing the 'Delete()' function:\n\n";
    list.Delete("Plum");
    list.Display();

    cout<<"\nThere is currently "<<list.Size()<<" items in the listnn";

    // demonstrate the "InsertAfter" function
    cout<<"\n** Now the word 'Bike' will be added to the list,"
        <<"\nright after the word 'Apple' using the "
        <<"'InsertAfter()' function:\n\n";
    list.InsertAfter("Apple","Bike");
    list.Display();

    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";

    // demonstrate the "InsertBefore" function
    cout<<"\n** Now the name 'Jessica' will be added to the list,"
        <<"\nright before the word 'Orange' using the "
        <<"'InsertBefore()' function:\n\n";
    list.InsertBefore("Orange","Jessica");
    list.Display();

    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";

    // demonstrate the "Replace" function
    cout<<"\n** The word 'Orange' will now be replaced with the name,"
        <<"\n'Kat' using the 'Replace()' function:\n\n";
    list.Replace("Orange","Kat");
    list.Display();

    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";
}// http://programmingnotes.org/
			
				
					
				
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						#include <iostream>
#include <string>
#include "LinkedList.h"
using namespace std;
 
int main()
{
    // declare variables, using a string as
    // the item type for the class. 
 
    // NOTE: you can also use an int, float, double etc.
    // instead of a string
    LinkedList<string> list;
 
    // demontrate the "InOrder" function
    cout<<"** These are names of fruits sorted in order"
        <<" using the 'InsertInOrder()' function:\n\n";
    list.InsertInOrder("Tomato");
    list.InsertInOrder("Orange");
    list.InsertInOrder("Apple");
    list.InsertInOrder("Plum");
    list.Display();
 
    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";
 
    // demonstrate the "Delete" function
    cout<<"\n** Here is the same list with the word 'Plum' deleted"
        << "\nusing the 'Delete()' function:\n\n";
    list.Delete("Plum");
    list.Display();
 
    cout<<"\nThere is currently "<<list.Size()<<" items in the listnn";
 
    // demonstrate the "InsertAfter" function
    cout<<"\n** Now the word 'Bike' will be added to the list,"
        <<"\nright after the word 'Apple' using the "
        <<"'InsertAfter()' function:\n\n";
    list.InsertAfter("Apple","Bike");
    list.Display();
 
    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";
 
    // demonstrate the "InsertBefore" function
    cout<<"\n** Now the name 'Jessica' will be added to the list,"
        <<"\nright before the word 'Orange' using the "
        <<"'InsertBefore()' function:\n\n";
    list.InsertBefore("Orange","Jessica");
    list.Display();
 
    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";
 
    // demonstrate the "Replace" function
    cout<<"\n** The word 'Orange' will now be replaced with the name,"
        <<"\n'Kat' using the 'Replace()' function:\n\n";
    list.Replace("Orange","Kat");
    list.Display();
 
    cout<<"\nThere is currently "<<list.Size()<<" items in the list\n\n";
}// http://programmingnotes.org/

Once compiled, you should get this as your output

** These are names of fruits sorted in order using the 'InsertInOrder()' function:
Apple Orange Plum Tomato There is currently 4 items in the list ** Here is the same list with the word 'Plum' deleted using the 'Delete()' function: Apple Orange Tomato There is currently 3 items in the list ** Now the word 'Bike' will be added to the list, right after the word 'Apple' using the 'InsertAfter()' function: Apple Bike Orange Tomato There is currently 4 items in the list ** Now the name 'Jessica' will be added to the list, right before the word 'Orange' using the 'InsertBefore()' function: Apple Bike Jessica Orange Tomato There is currently 5 items in the list ** The word 'Orange' will now be replaced with the name, 'Kat' using the 'Replace()' function: Apple Bike Jessica Kat Tomato
There is currently 5 items in the list

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

July 22, 2012 admin No comments

Click Here For Updated Version Of Program

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

REQUIRED KNOWLEDGE FOR THIS PROGRAM

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

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





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

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

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

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

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

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

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

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

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

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

C++ || Snippet – Singly Linked List Custom Template Queue Sample Code

July 14, 2012 admin No comments

This page will consist of sample code for a custom singly linked list template queue. This implementation differs from the previously highlighted doubly linked list in that this version uses a single node to store its data rather than using two separate nodes (front and rear).

Looking for sample code for a stack? Click here.

REQUIRED KNOWLEDGE FOR THIS SNIPPET

Structs Classes Template Classes - What Are They?'' Queue - What is it? FIFO - First In First Out #include < queue> Linked Lists - How To Use

This template class is a custom duplication of the Standard Template Library (STL) queue class. Whether you like building your own data structures, you simply do not like to use any inbuilt functions, opting to build everything yourself, or your homework requires you make your own data structure, this sample code is really useful. I feel its beneficial building functions such as this, that way you better understand the behind the scene processes.





		
		
			#include 'SingleQueue.h'
			
C++
			
			// ============================================================================
//    Author: K Perkins
//    Date:   Jul 14, 2012
//    Taken From: http://programmingnotes.org/
//    File:  SingleQueue.h
//    Description: This is a class which implements various functions
//          demonstrating the use of a queue. 
// ============================================================================
#include <iostream>

template <class ItemType>
class SingleQueue
{
public:
	SingleQueue();
		/*   Function: Constructor initializes queue 
			Precondition: None
			Postcondition: Defines private variables */
	bool IsEmpty();
		/*   Function: Determines whether queue is empty
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is empty and the
							 function = false if queue is not empty */
	bool  IsFull();
		/*   Function: Determines whether queue is full
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is full and the
							 function = false if queue is not full */
	void EnQueue(ItemType item);
		/*   Function: Adds new item to the back of the queue
			Precondition:  Queue has been created and is not full
			Postcondition: Item is in the queue */
	ItemType DeQueue();
		/*   Function: Returns and then deletes the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been removed and the queue
								order is maintained */
	ItemType Front();
		/*   Function: Returns (but does not delete) the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been returned and the queue
								order is maintained */
	ItemType Rear();
		/*   Function: Returns (but does not delete) the last item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The last item in the queue has been returned and the queue
								order is maintained */
	int Size();
          /*   Function: Return the current size of the queue
               Precondition: Queue has been initialized
               Postcondition: The size of the queue is returned */ 
	void MakeEmpty();
		/*   Function: Initializes queue to an empty state 
			Precondition: Queue has been created
			Postcondition: Queue no longer exists */
	~SingleQueue();
		/*   Function: Removes the queue 
			Precondition: Queue has been declared
			Postcondition: Queue no longer exists */
private:		
	struct  NodeType	
	{			
		ItemType currentItem;		
		NodeType* next;	
	};
	NodeType* head;	// front of queue 
	int size;
};

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

template<class ItemType>
SingleQueue<ItemType>::SingleQueue()
{
	head = NULL;
	size = 0;
}/* end of SingleQueue */

template<class ItemType>
bool SingleQueue<ItemType>::IsEmpty()
{
	return (head == NULL);
}/* end of IsEmpty */

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

template<class ItemType>
void SingleQueue<ItemType>::EnQueue(ItemType newItem)
{
	if(IsFull())
	{
		std::cout<<"nQUEUE FULLn";
	}
	else
	{
		NodeType* newNode = new NodeType;  // adds new node
		newNode-> currentItem = newItem;
		newNode-> next = NULL;
	
		if(IsEmpty())
		{
			head = newNode;
		}
		else
		{
			NodeType* tempPtr = head;
			while(tempPtr-> next != NULL)
			{
				tempPtr = tempPtr-> next;
			}
			tempPtr-> next = newNode;
		}
		++size;
	}
}/* end of EnQueue */

template<class ItemType>
ItemType SingleQueue<ItemType>::DeQueue() 
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    else
    {
        NodeType* tempPtr = head;  // temporary pointer
		
        ItemType item = head-> currentItem;
        head = head-> next;
        delete tempPtr;
        --size;
        return item;
    }	
}/* end of DeQueue */

template<class ItemType>
ItemType SingleQueue<ItemType>::Front() 
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    else
    {	
        ItemType item = head-> currentItem;
        return item;
    }	
}/* end of Front */

template<class ItemType>
ItemType SingleQueue<ItemType>::Rear() 
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    else
    {
        NodeType* tempPtr = head;  // temporary pointer

        while(tempPtr->next != NULL)
        {
                tempPtr = tempPtr-> next;
        }
        ItemType item = tempPtr-> currentItem;
        return item;
    }	
}/* end of Rear */

template<class ItemType>
int SingleQueue<ItemType>::Size()
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    return size;
}/* end of Size */

template<class ItemType>
void SingleQueue<ItemType>::MakeEmpty()
{
    if(!IsEmpty())
    {
        std::cout << "Destroying nodes ...n";
        while(!IsEmpty())
        {
            NodeType* tempPtr = head;
            //std::cout << tempPtr-> currentItem << 'n';
            head = head-> next;
            delete tempPtr;
        }
        size = 0;
    }
}/* end of MakeEmpty */

template<class ItemType>
SingleQueue<ItemType>::~SingleQueue() 
{
	MakeEmpty();
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: K Perkins
//    Date:   Jul 14, 2012
//    Taken From: http://programmingnotes.org/
//    File:  SingleQueue.h
//    Description: This is a class which implements various functions
//          demonstrating the use of a queue. 
// ============================================================================
#include <iostream>
 
template <class ItemType>
class SingleQueue
{
public:
	SingleQueue();
		/*   Function: Constructor initializes queue 
			Precondition: None
			Postcondition: Defines private variables */
	bool IsEmpty();
		/*   Function: Determines whether queue is empty
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is empty and the
							 function = false if queue is not empty */
	bool  IsFull();
		/*   Function: Determines whether queue is full
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is full and the
							 function = false if queue is not full */
	void EnQueue(ItemType item);
		/*   Function: Adds new item to the back of the queue
			Precondition:  Queue has been created and is not full
			Postcondition: Item is in the queue */
	ItemType DeQueue();
		/*   Function: Returns and then deletes the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been removed and the queue
								order is maintained */
	ItemType Front();
		/*   Function: Returns (but does not delete) the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been returned and the queue
								order is maintained */
	ItemType Rear();
		/*   Function: Returns (but does not delete) the last item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The last item in the queue has been returned and the queue
								order is maintained */
	int Size();
          /*   Function: Return the current size of the queue
               Precondition: Queue has been initialized
               Postcondition: The size of the queue is returned */ 
	void MakeEmpty();
		/*   Function: Initializes queue to an empty state 
			Precondition: Queue has been created
			Postcondition: Queue no longer exists */
	~SingleQueue();
		/*   Function: Removes the queue 
			Precondition: Queue has been declared
			Postcondition: Queue no longer exists */
private:		
	struct  NodeType	
	{			
		ItemType currentItem;		
		NodeType* next;	
	};
	NodeType* head;	// front of queue 
	int size;
};
 
//=========================  Implementation  ================================//
 
template<class ItemType>
SingleQueue<ItemType>::SingleQueue()
{
	head = NULL;
	size = 0;
}/* end of SingleQueue */
 
template<class ItemType>
bool SingleQueue<ItemType>::IsEmpty()
{
	return (head == NULL);
}/* end of IsEmpty */
 
template<class ItemType>
bool SingleQueue<ItemType>::IsFull()
{
	try
	{
		NodeType* location = new NodeType;
		delete location;
		return false;
	}
	catch(std::bad_alloc&)
	{
		return true;
	}
}/* end of IsFull */
 
template<class ItemType>
void SingleQueue<ItemType>::EnQueue(ItemType newItem)
{
	if(IsFull())
	{
		std::cout<<"nQUEUE FULLn";
	}
	else
	{
		NodeType* newNode = new NodeType;  // adds new node
		newNode-> currentItem = newItem;
		newNode-> next = NULL;
	
		if(IsEmpty())
		{
			head = newNode;
		}
		else
		{
			NodeType* tempPtr = head;
			while(tempPtr-> next != NULL)
			{
				tempPtr = tempPtr-> next;
			}
			tempPtr-> next = newNode;
		}
		++size;
	}
}/* end of EnQueue */
 
template<class ItemType>
ItemType SingleQueue<ItemType>::DeQueue() 
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    else
    {
        NodeType* tempPtr = head;  // temporary pointer
		
        ItemType item = head-> currentItem;
        head = head-> next;
        delete tempPtr;
        --size;
        return item;
    }	
}/* end of DeQueue */
 
template<class ItemType>
ItemType SingleQueue<ItemType>::Front() 
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    else
    {	
        ItemType item = head-> currentItem;
        return item;
    }	
}/* end of Front */
 
template<class ItemType>
ItemType SingleQueue<ItemType>::Rear() 
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    else
    {
        NodeType* tempPtr = head;  // temporary pointer
 
        while(tempPtr->next != NULL)
        {
                tempPtr = tempPtr-> next;
        }
        ItemType item = tempPtr-> currentItem;
        return item;
    }	
}/* end of Rear */
 
template<class ItemType>
int SingleQueue<ItemType>::Size()
{
    if(IsEmpty())
    {
        std::cout<<"nQUEUE EMPTYn";
    }
    return size;
}/* end of Size */
 
template<class ItemType>
void SingleQueue<ItemType>::MakeEmpty()
{
    if(!IsEmpty())
    {
        std::cout << "Destroying nodes ...n";
        while(!IsEmpty())
        {
            NodeType* tempPtr = head;
            //std::cout << tempPtr-> currentItem << 'n';
            head = head-> next;
            delete tempPtr;
        }
        size = 0;
    }
}/* end of MakeEmpty */
 
template<class ItemType>
SingleQueue<ItemType>::~SingleQueue() 
{
	MakeEmpty();
}// 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.

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

Use of the above template class is the same as its STL counterpart. Here is a sample program demonstrating its use.





		
		
			How To Use #include 'SingleQueue.h'
			
C++
			
			#include <iostream>
#include "SingleQueue.h"
using namespace std;

int main()
{
	// declare variables
	SingleQueue<char> charQueue;
	SingleQueue<int> intQueue;
	SingleQueue<double> doubleQueue;
	
	// ------ Char Example ------//
	char charArry[]="My Programming Notes Is A Big Help!";
	int counter=0;	
	while(charArry[counter]!='\0')
	{
		charQueue.EnQueue(charArry[counter]);
		++counter;
	}
	cout<<"charQueue has "<<charQueue.Size()<<" items in it "
		<<"and contains the text:n";
	while(!charQueue.IsEmpty())
	{
		cout<<charQueue.DeQueue();
	}
	cout<<endl;
	
	// ------ Int Example ------//
	int intArry[]={1,22,309,461,-92,66,7,8,1987,9,27,12};
	counter=0;
	while(counter < sizeof(intArry)/sizeof(intArry[0]))
	{
		intQueue.EnQueue(intArry[counter]);
		++counter;
	}
	cout<<"nintQueue has "<<intQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	counter=0;
	while(!intQueue.IsEmpty())
	{
		counter-=intQueue.DeQueue();
	}
	cout<<counter<<endl;
	
	// ------ Double Example ------//
	double doubleArry[]={31.62,2.8,43.9,4.4,19.87,6.23,7.787,68.99,9.6,3.540,12.04};
	double sum=0;
	counter=0;
	while(counter < sizeof(doubleArry)/sizeof(doubleArry[0]))
	{
		doubleQueue.EnQueue(doubleArry[counter]);
		++counter;
	}
	cout<<"ndoubleQueue has "<<doubleQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	while(!doubleQueue.IsEmpty())
	{
		sum+=doubleQueue.DeQueue();
	}
	cout<<sum<<endl;

	return 0;
}// http://programmingnotes.org/
			
				
					
				
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						#include <iostream>
#include "SingleQueue.h"
using namespace std;
 
int main()
{
	// declare variables
	SingleQueue<char> charQueue;
	SingleQueue<int> intQueue;
	SingleQueue<double> doubleQueue;
	
	// ------ Char Example ------//
	char charArry[]="My Programming Notes Is A Big Help!";
	int counter=0;	
	while(charArry[counter]!='\0')
	{
		charQueue.EnQueue(charArry[counter]);
		++counter;
	}
	cout<<"charQueue has "<<charQueue.Size()<<" items in it "
		<<"and contains the text:n";
	while(!charQueue.IsEmpty())
	{
		cout<<charQueue.DeQueue();
	}
	cout<<endl;
	
	// ------ Int Example ------//
	int intArry[]={1,22,309,461,-92,66,7,8,1987,9,27,12};
	counter=0;
	while(counter < sizeof(intArry)/sizeof(intArry[0]))
	{
		intQueue.EnQueue(intArry[counter]);
		++counter;
	}
	cout<<"nintQueue has "<<intQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	counter=0;
	while(!intQueue.IsEmpty())
	{
		counter-=intQueue.DeQueue();
	}
	cout<<counter<<endl;
	
	// ------ Double Example ------//
	double doubleArry[]={31.62,2.8,43.9,4.4,19.87,6.23,7.787,68.99,9.6,3.540,12.04};
	double sum=0;
	counter=0;
	while(counter < sizeof(doubleArry)/sizeof(doubleArry[0]))
	{
		doubleQueue.EnQueue(doubleArry[counter]);
		++counter;
	}
	cout<<"ndoubleQueue has "<<doubleQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	while(!doubleQueue.IsEmpty())
	{
		sum+=doubleQueue.DeQueue();
	}
	cout<<sum<<endl;
 
	return 0;
}// http://programmingnotes.org/

Once compiled, you should get this as your output

charQueue has 35 items in it and contains the text: My Programming Notes Is A Big Help!
intQueue has 12 items in it. The sum of the numbers in the queue is: -2817
doubleQueue has 11 items in it. The sum of the numbers in the queue is: 210.777 Press any key to continue . . .

C++ || Snippet – Doubly Linked List Custom Template Queue Sample Code

May 20, 2012 admin No comments

This page will consist of sample code for a custom doubly linked list template queue. This implementation is considered a doubly linked list because it uses two nodes to store data in the queue – a ‘front’ and a ‘rear’ node. This is not a circular linked list, nor does it link forwards and/or backwards.

Looking for sample code for a stack? Click here.

REQUIRED KNOWLEDGE FOR THIS SNIPPET

Structs Classes Template Classes - What Are They? Queue - What is it? FIFO - First In First Out #include < queue> Linked Lists - How To Use





		
		
			#include 'DoubleQueue.h'
			
C++
			
			// ============================================================================
//    Author: K Perkins
//    Date:   May 20, 2012
//    Taken From: http://programmingnotes.org/
//    File:  DoubleQueue.h
//    Description: This is a class which implements various functions
//          demonstrating the use of a queue. 
// ============================================================================
#include <iostream>

template <class ItemType>
class DoubleQueue
{
public:
	DoubleQueue();
		/*   Function: Constructor initializes queue 
			Precondition: None
			Postcondition: Defines private variables */
	bool IsEmpty();
		/*   Function: Determines whether queue is empty
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is empty and the
							 function = false if queue is not empty */
	bool  IsFull();
		/*   Function: Determines whether queue is full
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is full and the
							 function = false if queue is not full */
	void EnQueue(ItemType item);
		/*   Function: Adds new item to the back of the queue
			Precondition:  Queue has been created and is not full
			Postcondition: Item is in the queue */
	ItemType DeQueue();
		/*   Function: Returns and then deletes the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been removed and the queue
								order is maintained */
	ItemType Front();
		/*   Function: Returns (but does not delete) the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been returned and the queue
								order is maintained */
	ItemType Rear();
		/*   Function: Returns (but does not delete) the last item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The last item in the queue has been returned and the queue
								order is maintained */
	int Size();
          /*   Function: Return the current size of the queue
               Precondition: Queue has been initialized
               Postcondition: The size of the queue is returned */ 
	void MakeEmpty();
		/*   Function: Initializes queue to an empty state 
			Precondition: Queue has been created
			Postcondition: Queue no longer exists */
	~DoubleQueue();
		/*   Function: Removes the queue 
			Precondition: Queue has been declared
			Postcondition: Queue no longer exists */
private:
	struct  NodeType
	{
		ItemType currentItem;
		NodeType* next;
	};
	NodeType* front;	// front of queue 
	NodeType* rear;		// back of queue
	int size;
};

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

template<class ItemType>
DoubleQueue<ItemType>::DoubleQueue()
{
	front = NULL;
	rear = NULL;
	size = 0;
}/* end of DoubleQueue */

template<class ItemType>
bool DoubleQueue<ItemType>::IsEmpty()
{
	return (front == NULL);
}/* end of IsEmpty */

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

template<class ItemType>
void DoubleQueue<ItemType>::EnQueue(ItemType newItem)
{
	if(IsFull())
	{
		std::cout<<"nQUEUE FULLn";
	}
	else
	{
		NodeType* newNode = new NodeType; // adds new node
		newNode-> currentItem = newItem;
		newNode-> next = NULL;
	
		if(rear == NULL)
		{
			front = newNode;
		}
		else
		{
			rear-> next = newNode;			
		}
		rear = newNode;
		++size;
	}
}/* end of EnQueue */

template<class ItemType>
ItemType DoubleQueue<ItemType>::DeQueue() 
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	else
	{
		NodeType* tempPtr = front; // temporary pointer
		
		ItemType item = front-> currentItem;
		front = front-> next;

		if(front == NULL)
		{
			rear = NULL;
		}
		delete tempPtr;
		--size;
		return item;
	}	
}/* end of DeQueue */

template<class ItemType>
ItemType DoubleQueue<ItemType>::Front() 
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	else
	{
		return front-> currentItem;
	}	
}/* end of Front */

template<class ItemType>
ItemType DoubleQueue<ItemType>::Rear() 
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	else
	{		
		return rear-> currentItem;
	}	
}/* end of Rear */

template<class ItemType>
int DoubleQueue<ItemType>::Size()
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	return size;
}/* end of Size */

template<class ItemType>
void DoubleQueue<ItemType>::MakeEmpty()
{
	if(!IsEmpty())
	{
		std::cout << "Destroying nodes ...n";
		while(!IsEmpty())
		{
			NodeType* tempPtr = front;
			//std::cout << tempPtr-> currentItem << 'n';
			front = front-> next;
			delete tempPtr;
		}
		rear = NULL;
		size = 0;
	}
}/* end of MakeEmpty */

template<class ItemType>
DoubleQueue<ItemType>::~DoubleQueue() 
{
	MakeEmpty();
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: K Perkins
//    Date:   May 20, 2012
//    Taken From: http://programmingnotes.org/
//    File:  DoubleQueue.h
//    Description: This is a class which implements various functions
//          demonstrating the use of a queue. 
// ============================================================================
#include <iostream>
 
template <class ItemType>
class DoubleQueue
{
public:
	DoubleQueue();
		/*   Function: Constructor initializes queue 
			Precondition: None
			Postcondition: Defines private variables */
	bool IsEmpty();
		/*   Function: Determines whether queue is empty
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is empty and the
							 function = false if queue is not empty */
	bool  IsFull();
		/*   Function: Determines whether queue is full
			Precondition: Queue has been created
			Postcondition: The function = true if the queue is full and the
							 function = false if queue is not full */
	void EnQueue(ItemType item);
		/*   Function: Adds new item to the back of the queue
			Precondition:  Queue has been created and is not full
			Postcondition: Item is in the queue */
	ItemType DeQueue();
		/*   Function: Returns and then deletes the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been removed and the queue
								order is maintained */
	ItemType Front();
		/*   Function: Returns (but does not delete) the first item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The first item in the queue has been returned and the queue
								order is maintained */
	ItemType Rear();
		/*   Function: Returns (but does not delete) the last item in the queue
			Precondition:  Queue has been created and is not empty
			Postcondition: The last item in the queue has been returned and the queue
								order is maintained */
	int Size();
          /*   Function: Return the current size of the queue
               Precondition: Queue has been initialized
               Postcondition: The size of the queue is returned */ 
	void MakeEmpty();
		/*   Function: Initializes queue to an empty state 
			Precondition: Queue has been created
			Postcondition: Queue no longer exists */
	~DoubleQueue();
		/*   Function: Removes the queue 
			Precondition: Queue has been declared
			Postcondition: Queue no longer exists */
private:
	struct  NodeType
	{
		ItemType currentItem;
		NodeType* next;
	};
	NodeType* front;	// front of queue 
	NodeType* rear;		// back of queue
	int size;
};
 
//=========================  Implementation  ================================//
 
template<class ItemType>
DoubleQueue<ItemType>::DoubleQueue()
{
	front = NULL;
	rear = NULL;
	size = 0;
}/* end of DoubleQueue */
 
template<class ItemType>
bool DoubleQueue<ItemType>::IsEmpty()
{
	return (front == NULL);
}/* end of IsEmpty */
 
template<class ItemType>
bool DoubleQueue<ItemType>::IsFull()
{	
	try
	{
		NodeType* location = new NodeType;
		delete location;
		return false;
	}
	catch(std::bad_alloc&)
	{
		return true;
	}
}/* end of IsFull */
 
template<class ItemType>
void DoubleQueue<ItemType>::EnQueue(ItemType newItem)
{
	if(IsFull())
	{
		std::cout<<"nQUEUE FULLn";
	}
	else
	{
		NodeType* newNode = new NodeType; // adds new node
		newNode-> currentItem = newItem;
		newNode-> next = NULL;
	
		if(rear == NULL)
		{
			front = newNode;
		}
		else
		{
			rear-> next = newNode;			
		}
		rear = newNode;
		++size;
	}
}/* end of EnQueue */
 
template<class ItemType>
ItemType DoubleQueue<ItemType>::DeQueue() 
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	else
	{
		NodeType* tempPtr = front; // temporary pointer
		
		ItemType item = front-> currentItem;
		front = front-> next;
 
		if(front == NULL)
		{
			rear = NULL;
		}
		delete tempPtr;
		--size;
		return item;
	}	
}/* end of DeQueue */
 
template<class ItemType>
ItemType DoubleQueue<ItemType>::Front() 
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	else
	{
		return front-> currentItem;
	}	
}/* end of Front */
 
template<class ItemType>
ItemType DoubleQueue<ItemType>::Rear() 
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	else
	{		
		return rear-> currentItem;
	}	
}/* end of Rear */
 
template<class ItemType>
int DoubleQueue<ItemType>::Size()
{
	if(IsEmpty())
	{
		std::cout<<"nQUEUE EMPTYn";
	}
	return size;
}/* end of Size */
 
template<class ItemType>
void DoubleQueue<ItemType>::MakeEmpty()
{
	if(!IsEmpty())
	{
		std::cout << "Destroying nodes ...n";
		while(!IsEmpty())
		{
			NodeType* tempPtr = front;
			//std::cout << tempPtr-> currentItem << 'n';
			front = front-> next;
			delete tempPtr;
		}
		rear = NULL;
		size = 0;
	}
}/* end of MakeEmpty */
 
template<class ItemType>
DoubleQueue<ItemType>::~DoubleQueue() 
{
	MakeEmpty();
}// 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.

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

Use of the above template class is the same as its STL counterpart. Here is a sample program demonstrating its use.





		
		
			How To Use #include 'DoubleQueue.h'
			
C++
			
			#include <iostream>
#include "DoubleQueue.h"
using namespace std;

int main()
{
	// declare variables
	DoubleQueue<char> charQueue;
	DoubleQueue<int> intQueue;
	DoubleQueue<float> floatQueue;
	
	// ------ Char Example ------//
	char charArry[]="My Programming Notes Helped Me Succeed!";
	int counter=0;	
	while(charArry[counter]!='\0')
	{
		charQueue.EnQueue(charArry[counter]);
		++counter;
	}
	cout<<"charQueue has "<<charQueue.Size()<<" items in it "
		<<"and contains the text:n";
	while(!charQueue.IsEmpty())
	{
		cout<<charQueue.DeQueue();
	}
	cout<<endl;
	
	// ------ Int Example ------//
	int intArry[]={1,22,3,46,5,66,7,8,1987};
	counter=0;
	while(counter<9)
	{
		intQueue.EnQueue(intArry[counter]);
		++counter;
	}
	cout<<"nintQueue has "<<intQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	counter=0;
	while(!intQueue.IsEmpty())
	{
		counter-=intQueue.DeQueue();
	}
	cout<<counter<<endl;
	
	// ------ Float Example ------//
	float floatArry[]={41.6,2.8,43.9,4.4,19.87,6.23,7.787,68.99,9.6,81.540};
	float sum=0;
	counter=0;
	while(counter<10)
	{
		floatQueue.EnQueue(floatArry[counter]);
		++counter;
	}
	cout<<"nfloatQueue has "<<floatQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	while(!floatQueue.IsEmpty())
	{
		sum-=floatQueue.DeQueue();
	}
	cout<<sum<<endl;

	return 0;
}// http://programmingnotes.org/
			
				
					
				
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						#include <iostream>
#include "DoubleQueue.h"
using namespace std;
 
int main()
{
	// declare variables
	DoubleQueue<char> charQueue;
	DoubleQueue<int> intQueue;
	DoubleQueue<float> floatQueue;
	
	// ------ Char Example ------//
	char charArry[]="My Programming Notes Helped Me Succeed!";
	int counter=0;	
	while(charArry[counter]!='\0')
	{
		charQueue.EnQueue(charArry[counter]);
		++counter;
	}
	cout<<"charQueue has "<<charQueue.Size()<<" items in it "
		<<"and contains the text:n";
	while(!charQueue.IsEmpty())
	{
		cout<<charQueue.DeQueue();
	}
	cout<<endl;
	
	// ------ Int Example ------//
	int intArry[]={1,22,3,46,5,66,7,8,1987};
	counter=0;
	while(counter<9)
	{
		intQueue.EnQueue(intArry[counter]);
		++counter;
	}
	cout<<"nintQueue has "<<intQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	counter=0;
	while(!intQueue.IsEmpty())
	{
		counter-=intQueue.DeQueue();
	}
	cout<<counter<<endl;
	
	// ------ Float Example ------//
	float floatArry[]={41.6,2.8,43.9,4.4,19.87,6.23,7.787,68.99,9.6,81.540};
	float sum=0;
	counter=0;
	while(counter<10)
	{
		floatQueue.EnQueue(floatArry[counter]);
		++counter;
	}
	cout<<"nfloatQueue has "<<floatQueue.Size()<<" items in it.n"
		<<"The sum of the numbers in the queue is: ";
	while(!floatQueue.IsEmpty())
	{
		sum-=floatQueue.DeQueue();
	}
	cout<<sum<<endl;
 
	return 0;
}// http://programmingnotes.org/

Once compiled, you should get this as your output

charQueue has 39 items in it and contains the text: My Programming Notes Helped Me Succeed!
intQueue has 9 items in it. The sum of the numbers in the queue is: -2145
floatQueue has 10 items in it. The sum of the numbers in the queue is: -286.717

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