TheAlgorithms-C-Plus-Plus/data_structure/queue_using_array.cpp

/*
    Write a program to implement Linear Queue using array.

    Functions to implement
        Enqueue (Insertion)
        Dequeue (Deletion)

*/
#include <iostream>

#define MAXSIZE 10

class Queue_Array
{
    int front;
    int rear;
    int size;

 public:
    Queue_Array()
    {
        front = -1;
        rear = -1;
        size = MAXSIZE;
    }
    int *arr = new int[size];
    void enqueue(int);
    int dequeue();
    void display();
};

void Queue_Array::enqueue(int ele)
{
    if (rear == size - 1)
    {
        std::cout << "\nStack is full";
    }
    else if (front == -1 && rear == -1)
    {
        front = rear = 0;
        arr[rear] = ele;
    }
    else if (rear < size)
    {
        rear++;
        arr[rear] = ele;
    }
}

int Queue_Array::dequeue()
{
    int d;
    if (front == -1)
    {
        std::cout << "\nstack is empty ";
        return 0;
    }
    else if (front == rear)
    {
        d = arr[front];
        front = rear = -1;
    }
    else
    {
        d = arr[front++];
    }

    return d;
}

void Queue_Array::display()
{
    if (front == -1)
    {
        std::cout << "\nStack is empty";
    }
    else
    {
        for (int i = front; i <= rear; i++) std::cout << arr[i] << " ";
    }
}

int main()
{
    int op, data;

    Queue_Array ob;

    std::cout << "\n1. enqueue(Insertion) ";
    std::cout << "\n2. dequeue(Deletion)";
    std::cout << "\n3. Display";
    std::cout << "\n4. Exit";
    while (1)
    {
        std::cout << "\nEnter your choice ";
        std::cin >> op;
        if (op == 1)
        {
            std::cout << "Enter data  ";
            std::cin >> data;
            ob.enqueue(data);
        }
        else if (op == 2)
        {
            data = ob.dequeue();
            std::cout << "\ndequeue element is:\t" << data;
        }
        else if (op == 3)
        {
            ob.display();
        }
        else if (op == 4)
        {
            exit(0);
        }
        else
        {
            std::cout << "\nWrong choice ";
        }
    }
}