简单链式栈（C++模版技术实现）

//
// C++ 模版技术实现简单链式栈. 
// 

#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <stdexcept>

// 链式栈类模版前置声明.
template <typename T> class LinkedStack;
 
//
// 链式栈节点类模版. 
// 
template <typename T>
class Node
{
	friend class LinkedStack<T>;
	
private:
	T _value;
	Node<T> *_pNext;

public:
	Node(void)
		:_pNext(NULL)
	{ NULL; }

	Node(const T &val)
		: _value(val)
		, _pNext(NULL)
	{ NULL; }	
};

//
// 链式栈类模版. 
//  
template <typename T>
class LinkedStack
{
private:
	Node<T> *_pTop;
	
public:
	LinkedStack(void);	
	~LinkedStack(void);
	bool isEmpty(void) const;
	T getTop(void) const;
	void push(const T &val);
	T pop(void);

};


template <typename T>
inline LinkedStack<T>::LinkedStack(void)
	: _pTop(NULL)
{ NULL; } 


template <typename T>
LinkedStack<T>::~LinkedStack(void)
{	
	Node<T> *pDel = NULL;
	
	while (NULL != _pTop)
	{
		pDel = _pTop;
		_pTop = _pTop->_pNext;
		delete pDel;
	}
}


template <typename T>
inline bool LinkedStack<T>::isEmpty(void) const
{
	return NULL == _pTop;	
}
	
template <typename T>
inline T LinkedStack<T>::getTop(void) const
{
	if (isEmpty()) {
		throw std::underflow_error("栈空下溢.");
	}
	return _pTop->_value;
}
		
		
template <typename T>
inline void LinkedStack<T>::push(const T &val)
{
	Node<T> *pNew = new Node<T>(val);
	
	pNew->_pNext = _pTop;
	_pTop = pNew;
}
		

template <typename T>
inline T LinkedStack<T>::pop(void)
{
	if (isEmpty()) {
		throw std::underflow_error("栈空下溢.");
	}
	T value = _pTop->_value;
	Node<T>* pDel = _pTop;
	_pTop = _pTop->_pNext;
	delete pDel;
	
	return value;
}

//
// 测试栈. 
// 
int main(void)
{
	const size_t MAX_SIZE = 20;
	LinkedStack<int> stack;
	
	std::cout << "栈" << (stack.isEmpty() ? "" : "不") << "为空." << std::endl; 
	
	for (size_t i = 0; i < MAX_SIZE; ++i)
	{
		stack.push(i);
		std::cout << std::setw(3) << stack.getTop();
	}
	
	std::cout << std::endl;
	std::cout << "栈" << (stack.isEmpty() ? "" : "不") << "为空." << std::endl;  
	
	for (size_t i = 0; i < MAX_SIZE; ++i)
	{
		std::cout << std::setw(3) << stack.pop();
	}
	// std::cout << std::setw(3) << stack.pop();
	
	std::cout << std::endl;
	std::cout << "栈" << (stack.isEmpty() ? "" : "不") << "为空." << std::endl;
	
	return EXIT_SUCCESS;
}