Queue

#include <stdio.h>
int a[100],f=0,r=0,n,x=0;
void insert()
{
    if(x==0)
    {
        printf("Enter size of Queue:\n");
        scanf("%d",&n);
        x=1;
    }
    if(r==n && f==0)
    {
        printf("\nQueue is Full.\n");
    }
    else
    {
        printf("Enter Data:\n");
        int b;
        scanf("%d",&b);
        a[r]=b;
        r++;


    }

}
void del()
{
    if(r==0 && f==0)
    {
        printf("\nQueue is Empty.\n");
    }
    else
    {
        int i;
        printf("\nDeleted item is %d\n",a[f]);
        for(i=0;i<r-1;i++)
        {
            a[i]=a[i+1];
        }
        r--;
    }
}
void dis()
{
    if(r==0 && f==0)
    {
        printf("Queue is Empty.\n");

    }
    else
    {
        int i;
        for(i=f;i<r;i++)
        {
            printf("%d-->",a[i]);
        }
    }
}
int main()
{
    int i;
    while(1)
    {
        printf("\nEnter 1 for add,Enter 2 for Delete,3 for Display.\n");
        scanf("%d",&i);
        switch(i)
        {
        case 1:
            {
                insert();
                break;
            }
        case 2:
            {
                del();
                break;
            }
        case 3:
            {
                dis();
                break;
            }
        default:
            printf("\nEnter a option.\n");
        }
    }
}