Implementation of Queue using Link List (Menu driven Program)

Queue is linear data structure which operates on particular order of operation such as First in First out(FIFO).

Example: 

Line of student at admission counter, line of people at ATM machine etc

Pointer used for queue:
front-point to first arrived i.e. oldest element
rear-point to last arrived i.e.latest element 

Main operations

Enqueue:

Add element into queue at rear side, at every new arrival of element rear will point to latest arrivel element .

Dequeue:

Delete element of queue at front side,front will updated to next of front ,use dummy pointer for this operstion.

Node Structure:

struct node
{
    int info;
    struct node *ptr;
}*front,*rear,*temp,*front1;

Functions used in this program:

int frontelement();

void enq(int data);

void deq();

void empty();

void display();

void create();

void queuesize();

Menu Driven Program:

int no, ch, e;
    printf("\n 1 - Enque");
    printf("\n 2 - Deque");
    printf("\n 3 - Front element");
    printf("\n 4 - Empty");
    printf("\n 5 - Display");
    printf("\n 6 - Queuesize");
    printf("\n 7 - Exit");
    create();
    while (1)
    {
        printf("\n Enter choice : ");
        scanf("%d", &ch);
        switch (ch)
        {
        case 1:
            printf("Enter data for Enque: ");
            scanf("%d", &no);
            enq(no);
                        printf("\n Element of Queue after Enqueque operation:");
                        display();
           
            break;
        case 2:
            deq();
            printf("\n Element of Queue after deque operation:");
                        display();
            break;
        case 3:
            e = frontelement();
            if (e != 0)
                printf("Front element : %d", e);
            else
                printf("\n No front element in Queue as queue is empty");
            break;
        case 4:
            empty();
            break;
        case 5:
        display();
            break;
          
        case 6: queuesize();
            break;
           
        case 7:
            exit(0);
        default:
            printf("Wrong choice, Please enter correct choice  ");
            break;
        }
    }
}