C++ program to implement Queue using Linked Representation

Editorial Team — Mon, 31 Jan 2011 12:14:56 +0000

#include 
template
class Node
{
	friend LinkedQueue;
	private:
	T data;
	Node *link;
};
template
class LinkedQueue {
	public:
		LinkedQueue() {front = rear = 0;} // constructor
		~LinkedQueue(); // destructor
		int IsEmpty() const
		{return ((front) ? 0 : 1);}
		T First() const; // return first element
		T Last() const; // return last element
		LinkedQueue& Add(const T& x);
		LinkedQueue& Delete(T& x);
	private:
		Node *front;  // pointer to first node
		Node *rear;   // pointer to last node
};

	template
LinkedQueue::~LinkedQueue()
{// Queue destructor.  Delete all nodes.
	Node *next;
	while (front) {
		next = front->link;
		delete front;
		front = next;
	}
}
template
T LinkedQueue::First() const
{
	if (IsEmpty())   { cout<<"OutOfBounds()";  return -1; };
	return front->data;
}
template
T LinkedQueue::Last() const
{
	if (IsEmpty()) { cout<<"OutOfBounds()";    return -1; };
	return rear->data;
}
	template
LinkedQueue& LinkedQueue::Add(const T& x)
{
	Node *p = new Node;
	p->data = x;
	p->link = 0;
	if (front) rear->link = p;  // queue not empty
	else front = p;             // queue empty
	rear = p;
	return *this;
}
	template
LinkedQueue& LinkedQueue::Delete(T& x)
{
	if (IsEmpty()) {  cout<<"OutOfBounds()"; return *this; };
	x = front->data;
	Node *p = front;
	front = front->link;
	delete p;
	return *this;
}
void main(void)
{
	LinkedQueue Q;
	int x;
	Q.Add(1).Add(2).Add(3).Add(4);
	cout << "No queue add failed" << endl;
	cout << "Queue is now 1234" << endl;
	Q.Delete(x);
	cout << "Deleted " << x << endl;
	cout << Q.First() << " is at front" << endl;
	cout << Q.Last() << " is at end" << endl;
	Q.Delete(x);
	cout << "Deleted " << x << endl;
	Q.Delete(x);
	cout << "Deleted " << x << endl;
	Q.Delete(x);
	cout << "Deleted " << x << endl;
	cout << "No queue delete failed " << endl;
}

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C++ program to implement Queue using Linked Representation