circq.c

#include <stdio.h>
int q[20],n,f,r;

void insert(int x){
    r=(r+1)%n;
    if (f==r)
    {
        printf("Queue is full\n");
        return;
    }
    else if(r==-1){
        f=0;
        r=0;
        q[r]=x;
    }
    else{
        q[r]=x;
    }
}

void delete(){
	int d;
    if (f==-1 && r==-1){
        printf("Queue is empty\n");
        return;
    }
    else if (f==r)
    {
        d=q[f];
        f=-1;
        r=-1;
    }
    else{
        d=q[f];
        f=(f+1)%n;
    }
    printf("Deleted Element is %d",d);
}

void display(){
    int i;
    if (f==-1 && r==-1){
        printf("Queue is empty\n");
        return;
    }
    else if (f<=r){
        for(i=f;i<=r;i++){
            printf("%d ",q[i]);
        }
    }
    else{
        for(i=f;i<n;i++){
            printf("%d ",q[i]);
        }
        for (i=0;i<=r;i++){
            printf("%d ",q[i]);
        }
    }
}

void main (){
    int ch,x;
    printf("Enter the size of the queue\n");
    scanf("%d",&n);
    f=-1;
    r=-1;
    while(1){
        printf("Enter your choice\n");
        printf("1.Insert\n2.Delete\n3.Display\n4.Exit\n");
        scanf("%d",&ch);
        switch(ch){
            case 1:	
            	printf("Enter the element to be inserted : ");
                scanf("%d",&x);
                insert(x);
                r++;
                display();
                break;
            case 2:	
            	delete(x);
        		f++;
        		display();
                break;
            case 3:
            	display();
                break;
            case 4:
            	exit(0);
                break;
            default:printf("Invalid choice\n");
        }
    }
}