Programming: Cpp Program to Implement Queue Using Linked Lists

This C++ program, using iteration, implements the list of elements removed from the queue in first in first out mode using a linked list. A linked list is an ordered set of data elements, each containing a link to its successor.

Here is the source code of the C program to display the list of elements removed from the queue. The C++ program is successfully compiled and run on DevCpp, a C++ compiler. The program output is also shown below.

/*
 * C++ Program to Implement Queue using Linked List
 */
#include < iostream >
#include < stdio.h >
#include < conio.h >
using namespace std;
struct node
{
    int data;
    node *next;
}*front = NULL,*rear = NULL,*p = NULL,*np = NULL;
void push(int x)
{
    np = new node;
    np->data = x;
    np->next = NULL;
    if(front == NULL)
    {
        front = rear = np;
        rear->next = NULL;
    }
    else
    {
        rear->next = np;
        rear = np;
        rear->next = NULL;
    }
}
int remove()
{
    int x;
    if(front == NULL)
    {
        cout << "empty queue\n";
    }
    else
    {
        p = front;
        x = p->data;
        front = front->next;
        delete(p);
        return(x);
    }
}
int main()
{
    int n,c = 0,x;
    cout << "Enter the number of values to be pushed into queue\n";
    cin >> n;
    while (c < n)
    {
 cout << "Enter the value to be entered into queue\n";
 cin >> x;
        push(x);
        c++;
     }
     cout << "\n\nRemoved Values\n\n";
     while(true)
     {
        if (front != NULL)
            cout << remove() << endl;
        else
            break;
     }
     getch();
}

Output of above program

Output
Enter the number of values to be pushed into queue
6
Enter the value to be entered into queue
5
Enter the value to be entered into queue
4
Enter the value to be entered into queue
3
Enter the value to be entered into queue
2
Enter the value to be entered into queue
1
Enter the value to be entered into queue
0
 
Removed Values
 
5
4
3
2
1
0