17类模板

类模板

• 类成为类名和类型参数的组合
• 无论是一般类还是模板类，只有调用到的成员函数，才会出现在符号表上。

#pragma once
#include <iostream>
#include <cstring>
using namespace std;

template<typename T>
class SeqStack { //模板名称 + 类型参数列表 = 类名称
private:
	T* _pstack;
	int _top;
	int _size;

	void resize();
public:
	//构造和析构函数名可以不加类型参数列表，其它出现模板的地方都不能省略类型参数列表
	SeqStack<T>(int size = 5);
	SeqStack<T>(const SeqStack<T>& stack);
	~SeqStack<T>();
	SeqStack<T>& operator=(const SeqStack<T>& stack);

	void push(const T& val);
	void pop();
	T top()const;//只读的方法时候设计为常方法
	bool full()const;
	bool empty()const;

	int getlen()const { return _size; }
};
template<typename T>
void SeqStack<T>::resize()
{
	_size *= 2;
	T* tmp = new T[_size];
	for (int i = 0; i < _top; i++)
	{
		tmp[i] = _pstack[i];
	}
	delete[]_pstack;
	_pstack = tmp;
}

template<typename T>
SeqStack<T>::SeqStack<T>(int size)
	: _pstack(new T[size])
	, _size(size)
	, _top(0)
{}

template<typename T>
SeqStack<T>::SeqStack<T>(const SeqStack<T>& stack)
	:_size(stack._size)
	, _top(stack._top)
{
	delete[]_pstack;
	_pstack = new T[_size];
	for (int i = 0; i < _top; i++) {
		_pstack[i] = stack._pstack[i];
	}
}

template<typename T>
SeqStack<T>::~SeqStack<T>()
{
	delete[]_pstack;
	_pstack = nullptr;
}

template<typename T>
SeqStack<T>& SeqStack<T>::operator=(const SeqStack<T>& stack)
{
	if (&stack == this)
	{
		return *this;
	}
	delete[]_pstack;
	_top = stack._top;
	_size = stack._size;
	_pstack = new T[_size];
	for (int i = 0; i < _top; i++) {
		_pstack[i] = stack._pstack[i];
	}
}

template<typename T>
void SeqStack<T>::push(const T& val)
{
	if (full())
	{
		resize();
	}
	_pstack[top++] = val;
}

template<typename T>
void SeqStack<T>::pop()
{
	if (empty())
	{
		return;
	}
	_top--;
}


template<typename T>
T SeqStack<T>::top()const
{
	if (empty())
	{
		return;
	}
	return _pstack[--top];
}

template<typename T>
bool SeqStack<T>::full()const
{
	if (top == _size);
}

template<typename T>
bool SeqStack<T>::empty()const
{
	return(_top == 0);
}

int main()
{
	SeqStack<int> s1;
	cout << s1.getlen() << endl;
	return 0;
}