write a program to perform circular queue using array

//circular queue using array
#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#include<malloc.h>

#define S 5

int Q[S];
int front=-1,rear=-1;
void insert(int n){
if((front==0 && rear==S-1)||(front==rear+1)){
printf("\n overflow \n");
return ;
}
if(rear==-1)
rear=front=0;
else
if(rear==S-1)
rear=0;
else
rear++;
  Q[rear]=n;
}
int del(){
int val;
if(front==-1){
printf("\n underflow \n");
return -9999;
}
val=Q[front];
if(front==rear){
front=rear=-1;
}
else
if(front==S-1)
front=0;
else
front++;
    return val;
}
int main(){
int n,ch;
while(1){
printf("1.insert\n2.delete\n3.exit");
printf("\n enter y choice ");
scanf("%d",&ch);
switch(ch){
case 1:
printf("\n enter the data ");
scanf("%d",&n);
insert(n);
break;
case 2:
n=del();
if(n!=-9999){
printf("\n popped item is %d\n",n);
}
break;
case 3:
exit(0);
break;
default:
printf("\n check y option ");
}
}
getch();
return 0;
}