C++类模板实现栈

 使用类模板实现一个栈

包括拷贝构造、入栈、出栈、返回栈顶元素、判断栈是否为空为满

#include <iostream>

using namespace std;

template<typename T>
class SeqStack //模板名称 + 类型参数列表 = 类名称
{
public:
	//构造和析构函数名不用加<T>类型参数化列表 其他出现模板的地方都要加上类型参数化列表
	SeqStack(int size = 10)
		: _pstack(new T[size])
		, _top(0) 
		, _size(size)
	{}

	~SeqStack()
	{
		delete[]_pstack;
		_pstack = nullptr;
	}

	//拷贝构造函数
	SeqStack<T>(const SeqStack<T>& stack)
		:_top(stack._top)
		, _size(stack._size)
	{
		_pstack = new T[_size];
		//这里不要使用memcopy进行拷贝 可能会导致浅拷贝
		for (int i = 0; i < _top; ++i)
		{
			_pstack[i] = stack._pstack[i];
		}
	}

	//赋值运算符重载
    //确保在将一个SeqStack对象赋值给另一个对象时，不仅简单复制指针值还需要深拷贝数据
	SeqStack<T>& operator=(const SeqStack<T>& stack)
	{
		//防止自赋值
		if (this == &stack) 
			return *this;
		//删除原来空间
		delete[] _pstack;
		//赋值操作
		_top = stack._top;
		_size = stack._size;
		_pstack = new T[_size];
		for (int i = 0; i < _top; ++i)
		{
			_pstack[i] = stack._pstack[i];
		}
		return *this;
	}
	//入栈操作
	void push(const T& val);
	
	//出栈操作
	void pop()
	{
		if (empty())
			return;
		--_top;
	}
	//返回栈顶元素
	T top()const
	{
		if (empty())
			throw "stack is empty!";
		return _pstack[_top - 1];
	}
	//判断是否为满
	bool full() const
	{
		return _top == _size;
	}
	//判断是否为空
	bool empty() const
	{
		return _top == 0;
	}

private:
	T *_pstack;
	int _top;
	int _size;

	//底层栈底按2倍顺序扩容
	void expand()
	{
		T* ptmp = new T[_size * 2];
		for (int i = 0; i < _top; ++i)
		{
			ptmp[i] = _pstack[i];
		}
		delete[]_pstack;
		_pstack = ptmp;
		_size *= 2;
	}
};

//类外实现
template<typename T>
void SeqStack<T>::push(const T &val)
{
	if (full())
	{
		expand();
	}
	_pstack[_top++] = val;
}


int main()
{
	SeqStack<int>s1;
	s1.push(20);
	s1.push(78);
	s1.push(32);
	s1.push(15);
	s1.pop();
	cout << s1.top() << endl;
	return 0;
}