Circular_Queue.c

#include<stdio.h>
#include<stdlib.h>
#define max 100
int queue[max],n,x;
int front = -1;
int rear = -1;
void enqueue()
{
    if(front==-1 && rear==-1)
    {
        front=0;
        rear=0;
        printf("Enter the element : ");
        scanf("%d",&x);
        queue[rear]=x;
    }
    else if((rear+1)%n==front)
    printf("Queue is full !!!");
    else
    {
        rear=(rear+1)%n;
        printf("Enter the element : ");
        scanf("%d",&x);
        queue[rear]=x;
    }
}
void dequeue()
{
    int item;
    if(front==-1 && rear==-1)
    printf("Queue is empty !!!");
    else if(front==rear)
    {
        item=front;
        front=-1;
        rear=-1;
    }
    else
    {
        item=front;
        front=(front+1)%n;
    }
}
void peek()
{
    if(front==-1 && rear==-1)
    printf("Queue is empty !!!");
    else
    {
        printf("The front element is %d",queue[front]);
    }
}
void display()
{
    int i=front;
    if(front==-1 && rear==-1)
    printf("Queue is empty !!!");
    else
    {
        printf("Queue : ");
        while(i!=rear)
        {
            printf("%d ",queue[i]);
            i=(i+1)%n;
        }
        printf("%d",queue[rear]);
    }
}
int main()
{
    int op;
    printf("Enter the size of the queue : ");
    scanf("%d",&n);
    while(1)
    {
        printf("\n1. Insert an element\n2. Delete an element\n3. Peek\n4. Display the elements\n5. Exit\n\nEnter your choice : ");
        scanf("%d",&op);
        switch (op)
        {
        case 1 :
                enqueue();
                break;
        case 2 :
            dequeue();
            break;
        case 3 : 
            peek();
            break;
        case 4 :
            display();
            break;
        case 5 :
            exit(0);
    
        default:
            printf("Wrong choice !!! Try again\n");
            break;
        }
    }
}