Circular Queue in Data Structure

Example: Program for Circular Queue

#include<stdio.h>
#include<cstdlib>
#define max 6
int q[10],front=0,rear=-1;
int main()
{
    int ch;
    void insert();
    void delet();
    void display();

    printf("\nCircular Queue Operations\n");
    printf("1.Insert\n2.Delete\n3.Display\n4.Exit\n");
    while(1)
    {
        printf("Enter Your Choice:");
        scanf("%d",&ch);
        switch(ch)
        {
        case 1: insert();
            break;
        case 2: delet();
            break;
        case 3:display();
            break;
        case 4: exit(0);
        default:printf("Invalid option\n");
        }
    }
}
void insert()
{
    int x;
    if((front==0&&rear==max-1)||(front>0&&rear==front-1))
        printf("Queue is Overflow\n");
    else
    {
        printf("Insert Element :");
        scanf("%d",&x);
        if(rear==max-1&&front>0)
        {
            rear=0;
            q[rear]=x;
        }
        else
        {
            if((front==0&&rear==-1)||(rear!=front-1))
             q[++rear]=x;
        }
    }
}
void  delet()
{
    int a;
    if((front==0)&&(rear==-1))
    {
    printf("Queue is Underflow\n");
    exit(0);
    }
    if(front==rear)
    {
        a=q[front];
        rear=-1;
        front=0;
    }
    else
        if(front==max-1)
        {
            a=q[front];
            front=0;
        }
        else a=q[front++];
        printf("Deleted Element is : %d\n",a);
}
void display()
{
    int i,j;
    if(front==0&&rear==-1)
    {
        printf("Queue is Underflow\n");
        exit(0);
    }
    if(front>rear)
    {
        for(i=0;i<=rear;i++)
            printf("\t%d",q[i]);
        for(j=front;j<=max-1;j++)
            printf("\n \t%d",q[j]);
        printf("\nRear is at %d\n",q[rear]);
        printf("\nFront is at %d\n",q[front]);
    }
    else
    {
        for(i=front;i<=rear;i++)
        {
            printf("\t%d",q[i]);
        }
        printf("\nRear is at %d\n",q[rear]);
        printf("\nFront is at %d\n",q[front]);
    }
    printf("\n");
}