Write a C program to simulate the working of an Circular Queue using an array. Provide the operations CQINSERT, CQDELETE and CQDISPLAY. Check the Circular Queue status for empty and full.

#include<stdio.h>
#include<conio.h>
#define n 3
int front=-1,rear=-1;
int queue[n],item;
int isempty();
main()
{
 void cqinsert();
 void cqdelete();
 void cqdisplay();

 int choice;
 clrscr();
 while(1)
 {
  printf("\n circular queue simulator");
  printf("\n 1.insert");
  printf("\n 2.display");
  printf("\n 3.delete");
  printf("\n 4.exit ");
  printf("\n enter your choice");
  scanf("%d",&choice);
  switch(choice)
  {
   case 1:cqinsert();
   break;
   case 2:cqdisplay();
   break;
   case 3:cqdelete();
   break;
   case 4:exit();
    break;
    default:printf("\n invalid entry ");
    }
    }
    }
   void cqinsert()
   {
    if(cqfull())
    {
     printf("\n queue is full - overflow");
     return;
    }
   else
   {
    printf("\n enter the element to be added:");
    scanf("%d",&item);
    if(front==-1)
    front=rear=0;
    else
    rear=(rear+1)%n;
    queue[rear]=item;
    }
    return;
    }
    void cqdisplay()
    {
    int i;
    if(cqempty())
    {
    printf ("queue is empty");
    return;
    }
    printf("\n queue elements\n");
    if(front<=rear)
    {
    for(i=front;i<=n-1;i++)
    printf("\n%d",queue[i]);
    }
    if(front>rear)
    {
    for(i=front;i<=n-1;i++)
    printf("\n%d",queue[i]);
    for(i=0;i<=rear;i++)
    printf("%n%d",queue[i]);
    }
    }
    void cqdelete()
    {
    int item;
    if(cqempty())
    {
    printf("\n underflow");
    return;
    }
    else
    {
    item=queue[front];
    printf("\n deleted elements is%d",item);
    queue[front]=0;
    if(front==rear)
    {
    printf("\n queue has a single element");
    front=rear=-1;
    }
    else
    front=(front+1)%n;
    }
    return;
    }
    int cqempty()
    {
    if((front==-1)&&(rear==-1))
    return 1;
    else
    return 0;
    }
    int cqfull()
    {
    if((front==1)*(rear+1)%n)
    return 1;
    else
    return 0;
    }