Queue

#include<stdio.h>
#include<stdlib.h>
#define max 5

int que[max];
int rear=-1;
int front=-1;





void main()
{
    int choice;

     printf("\t1.Insert element to queue\n");
         printf("\t2.Delete element to queue\n");
          printf("\t3.Display queue element\n");
           printf("\t4.Quit\n");

    while(1)
    {


           printf("\nEnter your choice:");
           scanf("%d", &choice);

           switch(choice)
           {
           case 1:
            insert();
            break;
           case 2:
            delete();
            break;
           case 3:
            display();
            break;
           case 4:
            exit(1);  //exit from the loop
           default:
            printf("\nWrong choice");
            printf("Do you want to continue type 1 ");

           }
         fflush(stdin);
    }
}

     void insert()
    {
        int add;
        if(rear==max-1)
            printf("\nQueue is overflow\n");
        else
        {
            if (front==-1)
                front=0;
            printf("\nInsert the element to queue\n");
            scanf("%d", &add);
            rear=rear+1;
            que[rear]=add;
        }
    }
   int delete()
    {
        if(front==-1 ||front>rear)
        {
            printf("\nQueue is underflow\n");

            return ;
        }
        else
        {
            printf("Queue element  delete  :\n");
            front=front+1;
        }
    }
   void  display()

    {
        int i;
        if(front==-1)
            printf("Queue is empty\n");
        else
            {
            printf("Queue is:\n");
              for(i=front; i<=rear; i++)
            printf("%d\n", que[i]);
            }
            return 0;
    }