Queue.cpp

#include <bits/stdc++.h> 
using namespace std; 

struct QNode { 
	int data; 
	QNode* next; 
	QNode(int d) 
	{ 
		data = d; 
		next = NULL; 
	} 
}; 

struct Queue { 
	QNode *front, *rear; 
	Queue() 
	{ 
		front = rear = NULL; 
	} 

	void enQueue(int x) 
	{ 

		// Create a new LL node 
		QNode* temp = new QNode(x); 

		// If queue is empty, then 
		// new node is front and rear both 
		if (rear == NULL) { 
			front = rear = temp; 
			return; 
		} 

		// Add the new node at 
		// the end of queue and change rear 
		rear->next = temp; 
		rear = temp; 
	} 

	// Function to remove 
	// a key from given queue q 
	void deQueue() 
	{ 
		// If queue is empty, return NULL. 
		if (front == NULL) 
			return; 

		// Store previous front and 
		// move front one node ahead 
		QNode* temp = front; 
		front = front->next; 

		// If front becomes NULL, then 
		// change rear also as NULL 
		if (front == NULL) 
			rear = NULL; 

		delete (temp); 
	} 
}; 

int main() 
{ 

	Queue q; 
	q.enQueue(10); 
	q.enQueue(20); 
	q.deQueue(); 
	q.deQueue(); 
	q.enQueue(30); 
	q.enQueue(40); 
	q.enQueue(50); 
	q.deQueue(); 
	cout << "Queue Front : " << (q.front)->data << endl; 
	cout << "Queue Rear : " << (q.rear)->data; 
}