Write a C program to simulate the working of an ordinary Queue using an array. Provide the operations QINSERT, QDELETE and QDISPLAY. Check the Queue status for empty and full.

#include<stdio.h>
#include<conio.h>
#define n 3
int front=-1,rear=-1;
int queue[n];
main()
{
 void qinsert(int);
 void qdelete();
 void qdisplay();
 int isfull();
 int isempty();
 int choice,item;
 clrscr();
 while(1)
 {
  printf("\n QUEUE PROGRAM \n");
  printf("\n 1.insert");
  printf("\n 2.delete");
  printf("\n 3.display");
  printf("\n 4.exit");
  printf("\n enter your choice :");
  scanf("%d",&choice);
  switch(choice)
  {
   case 1:printf("enter the number to be inserted :");
      scanf("%d",&item);
      qinsert(item);
      break;
   case 2:qdelete();
      break;
   case 3:qdisplay();
      break;
   case 4:exit();
   default:printf("\n invalid choice !!!");
    }
   }
 }
 void qinsert(int item)
 {
  if(isfull())
  {
   printf("\n overflow");
   return;
  }
  if(front && rear==-1)
   front=rear=0;
   else
   rear=rear+1;
   queue[rear]=item;
   if(rear==n-1)
   printf("\n queue is full");
   return;
  }
  void qdisplay()
  {
   int i;
   if(isempty())
   {
    printf("\n no elements is the queue ");
    return;
   }
   else
   {
    for(i=front;i<=rear;i++)
    printf("\n%d",queue[i]);
   }
   return;
  }
  void     qdelete()
  {
   int item;
   if(isempty())
   {
    printf("\n underflow");
    return;
    }
    else
    item=queue[front];
    printf("the elements deleted is %d ",item);
    if(front==rear)
    {
     front=-1;
     rear=-1;
     }
     else
     front++;
     return;
    }
    int isfull()
    {
     if(rear==n-1)
     return 1;
     else
     return 0;
    }
    int isempty()
    {
     if(front==-1)
     return 1;
     else
     return 0;
     }