C++实现栈

1.栈 

定义：栈是只允许末端进行插入和删除的线性表，具有先进后出或先进后出的特性

栈用数组实现较好，因为它只在尾上进行操作，进行增删比较方便。

1.栈

<span style="font-family:Microsoft YaHei;font-size:18px;">#pragma once

//栈具有后进先出的原则，
template<class T>
class Stack
{
public:
	//构造函数
	Stack()
		:_a(NULL)
		, _top(0)
		, _capcity(0)
	{}
	//析构函数
	~Stack()
	{
		Clear();
	}
	//push
	void PushBack(const T& x)
	{
		//1.先检查容量 2.向数据中插入新数据 3.++_top
		CheckCapcity();
		_a[_top++] = x;
	}
	//pop
	void PopBack()
	{
		if (_top == 0)
		{
			cout << "NULL" << endl;;
			return;  //记得加这句，不然停不下来，越界访问,有bug
		}
		else
			--_top;
	}
	//size
	int Size()
	{
		return _top;
	}
	//empty
	bool Empty()
	{
		return _top == 0;
	}
	//top
	T& Top()
	{
		return _a[_top-1];
	}
	void Print()
	{
		for (int i = 0; i < _top; i++)
		{
			cout << _a[i] << " ";
		}
		cout << endl;
	}
protected:
	void CheckCapcity()
	{
		if (_top == _capcity)
		{//扩充的是_capcity，所以只改变_capcity，其他的不用动
			_capcity = _capcity * 2 + 3;
			T* tmp = new T[_capcity]; //重新开辟空间
			for (int i = 0; i < _top; i++)
			{
				tmp[i] = _a[i];  //将数据都拷贝到新空间中
			}
			delete[] _a;		 //释放原空间，
			_a = tmp;            //然后指针重新指向新空间
		}
	}
	void Clear()
	{
		if (_a!=NULL)
		{
			delete[] _a;
			_top = 0;
			_capcity = 0;
		}
	}
	
protected:
	T* _a;  //栈底层封装数组，利用数组实现栈，这样做就可以限制只在尾上做处理
	size_t _top;//指向最上面的元素，相当关于以前数组的的size
	size_t _capcity;//当前栈的总容量
};</span>

测试用例：

<span style="font-family:Microsoft YaHei;font-size:18px;">#define _CRT_SECURE_NO_WARNINGS 1



#include<iostream>
using namespace std;
#include"Stack.h"


//Test Push
void Test1()
{
	Stack<int> s1;
	s1.Push(1);
	s1.Push(2);
	s1.Push(3);
	s1.Push(4);
	s1.Push(5);
	while (!s1.Empty())
	{
		cout << s1.Top() << endl;
		s1.Pop();
	}
}



//Test Pop
void Test2()
{
	Stack<int> s1;
	s1.Push(1);
	s1.Push(2);
	s1.Push(3);
	s1.Push(4);
	s1.Push(5);

	s1.Pop();
	s1.Pop();
	s1.Pop();
	s1.Pop();
	s1.Pop();
	s1.Pop();
	s1.Pop();
	while (!s1.Empty())
	{
		cout << s1.Top() << endl;
		s1.Pop();
	}
}



//Test  size()
void Test3()
{
	Stack<int> s1;
	s1.Push(1);
	cout << s1.size() << endl;
	s1.Push(2);
	cout << s1.size() << endl;
	s1.Push(3);
	cout << s1.size() << endl;
	s1.Push(4);
	cout << s1.size() << endl;
	s1.Push(5);
	cout << s1.size() << endl;
}

//test empty
void Test4()
{
	Stack<int> s1;
	s1.Push(1);
	s1.Push(2);

	s1.Pop();
	s1.Pop();
	cout << s1.Empty() << endl;
}

//test
void Test5()
{
	Stack<int> s1;
	s1.Push(1);
	cout<<s1.Top()<<endl;
	s1.Push(2);
	cout << s1.Top() << endl;
	s1.Push(3);
	cout << s1.Top() << endl;
	s1.Push(4);
	cout << s1.Top() << endl;
	s1.Push(5);
	cout << s1.Top() << endl;

}
int main()
{
	//Test1();
	//Test2();
	//Test3();
	//Test4();
	Test5();
	system("pause");
	return 0;
}


</span>

如有不正确的地方，希望能够指出，一起学习，谢谢了。