circular_queue.cpp

#include <iostream>
using namespace std;

class CircularQueue{
    int *arr;
    int front;
    int rear;
    int size;

    public:

    CircularQueue(int n){
        size = n;
        arr = new int[n];
        front = rear = -1;
    }

    bool enqueue(int value){
        //to check whther queue is full
        if( (front == 0 && rear == size-1) || (rear == (front-1)%(size-1) ) ) {
            cout << "Queue is Full";
            return false;
        }
        else if(front == -1) //first element to push
        {
			front = rear = 0;
            
        }
        else if(rear == size-1 && front != 0) {
            rear = 0; //to maintain cyclic nature
        }
        else
        {//normal flow
            rear++;
        }
        //push inside the queue
        arr[rear] = value;
        
        return true;
    }

    int dequeue(){
        if(front == -1){//to check queue is empty
            cout << "Queue is Empty " << endl;
            return -1;
        }
        int ans = arr[front];
        arr[front] = -1;
        if(front == rear) { //single element is present
            front = rear = -1;
        }
        else if(front == size - 1) {
            front = 0; //to maintain cyclic nature
        }
        else
        {//normal flow
            front++;
        }
        return ans;
    }
};

int main()
{
    CircularQueue cq(5);
    
    cq.enqueue(2);   
    cq.enqueue(4);
    cq.enqueue(6);
    cq.enqueue(9);
    cq.enqueue(1);
    

    cq.dequeue();
    cq.dequeue();

    cq.enqueue(11);
    cq.enqueue(7);


}