3.3 Circular Queue

#include<stdio.h>
#define q_s 3
#define r rear
#define f front
int r,f;
int queue[q_s];
void Insertion(int ele){
    if( (r+1) % q_s == f ) {
        printf("\nQueue is full");
        return;
    }
    else if (r == -1 && f == -1){
        r = f = 0;
    }
    else r =(r+1) % q_s;
    queue[r] = ele;
}
void Deletion(){
    if(r==-1) printf("\nQueue is already empty");
    else if (r == f){
        queue[f]=0;
        r = f = -1;
    }
    else queue[f++] = 0;
}
void Print(){
    if(r == -1) {
        printf("\nQueue is empty");
        return;
    }
    else{
        int i;
        for( i=f ; i != r ; i = (i+1)%q_s)
            printf("%d ",queue[i]);
        printf("%d ",queue[i]);
    }
}
int main()
{
    r = f = -1;
    int key,choice,element;
    while(1){
        printf("\n1 for insertion \n2 for deletion\nAny key to just print the queue\n");
        scanf("%d",&choice);
        if(choice==1){
            printf("\nEnter the element ");
            scanf("%d",&element);
            Insertion(element);
        }
        else if(choice==2){
            Deletion();
        }
        else Print();

        printf("\n1 - for repeat and any key to exit ");
        scanf("%d",&key);
        if(key!=1)break;
    }
    return 0;
}