circularQue.cpp

#include <iostream>
using namespace std;

class Queue
{
public:
    int *arr, front, rear, size;

    Queue()
    {
        front = -1;
        rear = -1;
    }
};

bool isFull(Queue *Q)
{
    if (Q->front == 0 && Q->rear == Q->size - 1)
    {
        return true;
    }
    if (Q->front == Q->rear + 1)
    {
        return true;
    }
    return false;
}
bool isEmpty(Queue *Q)
{
    if (Q->front == -1)
        return true;
    else
        return false;
}

void Enqueue(Queue *Q)
{
    int value;
    if (isFull(Q))
    {
        cout << endl
             << "Queue is full!\n";
    }
    else
    {
        if (Q->front == -1)
        {
            Q->front = 0;
            Q->rear = 0;
        }
        else
        {

            Q->rear = (Q->rear + 1) % Q->size;
        }
        cout << "Enter the value : ";
        cin >> value;
        Q->arr[Q->rear] = value;
        cout << "Enqueued " << value << " in the Queue\n";
    }
}

int Dequeue(Queue *Q)
{
    int value;
    if (isEmpty(Q))
    {
        cout << "Queue is empty!\n"
             << endl;
    }
    else
    {
        value = Q->arr[Q->front];
        cout << endl
             << "Dequeued " << value << " from Q\n";
        if (Q->front == Q->rear)
        {
            Q->front = -1;
            Q->rear = -1;
        }
        else
        {
            if (Q->front == Q->size - 1)
            {
                Q->front = 0;
            }
                else
                {
                    Q->front = (Q->front + 1) % Q->size;
                }
            }
        }
    }

void Display(Queue *Q)
{
    if (!isEmpty(Q))
    {
        cout << "Elements of Queue are : ";
        for (int i = Q->front + 1; i <= Q->rear; i++)
        {
            cout << Q->arr[i];
        }
    }
    else
    {
        cout << "Queue is empty\n";
    }
}

int main()
{

    Queue *Q = new Queue();
    cout << "Enter the size of the Queue : ";
    cin >> Q->size;
    Q->arr = new int(Q->size);

    int choice;
    do
    {
        cout << "1. Enqueue\n2. Dequeue\n3. Display\n4. Exit\n\n";
        cout << "Enter your choice : ";
        cin >> choice;
        switch (choice)
        {
        case 1:
            Enqueue(Q);
            break;
        case 2:
            Dequeue(Q);
            break;
        case 3:
            Display(Q);
            break;
        case 4:
            exit(0);
            break;
        default:
            cout << "Sorry, invalid choice!\n";
            break;
        }
    } while (choice != 4);
    return 0;
}