C Program to Implement a Queue using an Array

#include < stdio.h>
 
#define MAX 50
int queue_array[MAX];
int rear = - 1;
int front = - 1;
main()
{
    int choice;
    while (1)
    {
        printf("1.Insert element to queue \n" );
        printf("2.Delete element from queue \n" );
        printf("3.Display all elements of queue \n" );
        printf("4.Quit \n" );
        printf("Enter your choice : " );
        scanf("%d" , &choice);
        switch (choice)
        {
            case 1:
            insert();
            break;
            case 2:
            delete();
            break;
            case 3:
            display();
            break;
            case 4:
            exit(1);
            default:
            printf("Wrong choice \n" );
        } /*End of switch*/
    } /*End of while*/
} /*End of main()*/
insert()
{
    int add_item;
    if (rear == MAX - 1)
    printf("Queue Overflow \n" );
    else
    {
        if (front == - 1)
        /*If queue is initially empty */
        front = 0;
        printf("Inset the element in queue : " );
        scanf("%d" , &add_item);
        rear = rear + 1;
        queue_array[rear] = add_item;
    }
} /*End of insert()*/
 
delete()
{
    if (front == - 1 || front > rear)
    {
        printf("Queue Underflow \n" );
        return ;
    }
    else
    {
        printf("Element deleted from queue is : %d\n" , queue_array[front]);
        front = front + 1;
    }
} /*End of delete() */
display()
{
    int i;
    if (front == - 1)
        printf("Queue is empty \n" );
    else
    {
        printf("Queue is : \n" );
        for (i = front; i <= rear; i++)
            printf("%d " , queue_array[i]);
        printf("\n" );
    }
} /*End of display() */

Output

  1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  1 
Inset the element  in  queue :  10 
 1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  1 
Inset the element  in  queue :  15 
 1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  1 
Inset the element  in  queue :  20 
 1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  1 
Inset the element  in  queue :  30 
 1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  2 
Element deleted from queue is :  10 
 1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  3 
Queue is :
 15   20   30 
 1 .Insert element to queue
 2 .Delete element from queue
 3 .Display all elements of queue
 4 .Quit
Enter your choice :  4 

For More Details Please Visit Ictjobs.info