简单顺序栈（C++模版技术实现）

//
// C++ 模版技术实现简单顺序栈. 
// 

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

//
// 顺序栈类模版.  
//
template <typename T>
class Stack
{
private:
	int _top;
	size_t _size;
	T *_pStack;
	static const size_t _DEF_SIZE = 20;
	// 
	// _MIN_TOP 不应为 size_t 类型.
	// 因为 size_t 类型与 int 类型变量比较时会将 int 类型转换为 size_t 类型. 
	//
	static const int _MIX_TOP = 0; 
	
public:
	Stack(const size_t size = _DEF_SIZE)
		: _top(_MIX_TOP - 1)
		, _size(size)
	{ _pStack = new T[_size]; }
	
	
	~Stack(void)
	{ delete[] _pStack; }
	
	
	bool isEmpty(void) const
	{ return _MIX_TOP > _top; }
	
	
	bool isFull(void) const
	{ return _size - 1 == _top; }
	
	
	T getTop(void) const
	{
		if (isEmpty()) {
			throw std::underflow_error("栈空下溢 !"); 
		}
		return _pStack[_top]; 
	}
	
	
	void push(const T &val)
	{
		if (isFull()) {
			throw std::overflow_error("栈满上溢 !");
		}
		_pStack[++_top] = val;
	}
	
	
	T pop(void)
	{ 
		if (isEmpty()) {
			throw std::underflow_error("栈空下溢 !");
		}
		return _pStack[_top--];
	}
};

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