ArrayQueue.cpp

// ConsoleApplication11.cpp : main project file.

#include "stdafx.h"
#include <iostream>
#include <cstdlib>
using namespace std;

const int MAX_SIZE = 100;

class ArrayQueue
{
private:
	int data[MAX_SIZE];
	int front;
	int rear;
public:
	ArrayQueue()
	{
		front = -1;
		rear = -1;
	}


	int Size()
	{

		if (rear == -1) {
			return 0;
		}

		if (rear < front)
		{
			return MAX_SIZE - (front - rear) + 1;
		}

		return rear - front + 1;
	}

	void Enqueue(int element)
	{
		// Don't allow the queue to grow more
		// than MAX_SIZE - 1
		if (Size() == MAX_SIZE) {
			cout << "Max size reached\n";
			return;
		}

		// MOD is used so that rear indicator
		// can wrap around
		rear = (rear+1) % MAX_SIZE;
		data[rear] = element;
		if (front == -1) {
			front = 0;
		}
		
	}

	int Dequeue()
	{
		if (isEmpty()) {
			cout << "queue is empty!\n";
			return -1;
		}

		int ret = data[front];

		// if the last element is dequeued
		// queue is turned in it's initial state
		if (front == rear) {
			front = -1;
			rear = -1;
			return ret;
		}

		// MOD is used so that front indicator
		// can wrap around
		front = (front+1) % MAX_SIZE;

		return ret;
	}

	int Front()
	{
		if (isEmpty()) {
			cout << "Queue is empty\n";
			return -1;
		}

		return data[front];
	}



	bool isEmpty()
	{
		return (rear == -1) ? true : false;
	}
};

int main()
{
	ArrayQueue q;

	if (q.isEmpty())
	{
		cout << "Queue is empty" << endl;
	}

	// Enqueue elements
	q.Enqueue(100);
	q.Enqueue(200);
	q.Enqueue(300);

	cout << q.Dequeue() << "(100?)\n";
	cout << q.Dequeue() << "(200?)\n";


}