C++之模板类stack实例

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#include <iostream>
using namespace std;
//const int CAP = 5;

//typedef int T;
//Array<T>
template <class T>
class Stack
{
private:
	int n;//已放元素个数
//	T arr[CAP];
	T* arr;
	int cap;  //将固定大小的arr 改成 可调大小的arr cap为容量
public:
	Stack(int cap=3):n(0),arr(new T[cap]),cap(cap){/*cout<<"Stack()"<<endl;*/}
	~Stack(){delete[] arr; /*cout<<"~Stack()"<<endl;*/}
	Stack(const Stack& s); //拷贝构造函数  是为arr 和 cap服务 因为是在类里面需要把东西给构造出来
	Stack& operator=(const Stack& s); //下面涉及到对cap的赋值 需要用到“＝” 则用到运算符重载
 //拷贝构造函数，运算符重载，模板类三件套
	void push(const T& t)
	{
		if(full())throw "stack overflow";
		arr[n++]=t;
	}
	void pop()
	{
		if(empty())throw "stack empty";
		--n;
	}
	T top()
	{
		if(empty())throw "stack empty";
		return arr[n-1];
	}
	bool empty(){return n==0;}
	bool full(){return n==cap;}
	int& size(){return n;} //*
	void clear(){n=0;}
	int capacoty(){return cap;}
};

template <typename T>
Stack<T>::Stack(const Stack& s)
{
		cout<<"Stack(copy)"<<endl;
		n=s.n;
		arr = new T[s.cap];
		cap = s.cap;
		for(int i=0;i<n;++i)
		{
			arr[i] = s.arr[i];
		}
	}

template <typename T>
Stack<T>& Stack<T>:: operator=(const Stack& s)
	{
		if(this==&s)return *this;
		delete[] arr;
		n=s.n;
		arr = new T[s.cap];
		cap = s.cap;
		for(int i=0;i<n;++i)
		{
			arr[i] = s.arr[i];
		}
		return *this;
	}

template <typename T>
void show(Stack<T> &s) //T s
{
	int n = s.size();
	while(!s.empty())
	{
		cout<<s.top()<<" ";
		s.pop();
	}
	cout<<endl;
	s.size() = n;
}

int main004()
{
	try {
		int* p = new int; //new int 本就是声明一个空间是地址 因此p也必须是指针
	//	*p = 4;
		cout<<"*p="<<*p<<endl;
//		int* pi = new int;
//		double* pd = new double;
//		string* ps = new string; //string(); string s;
//		string* ps2 = new string(3); //string(int) NO 建内存的本质是调用构造函数
//		string* ps22 = new string(3,'\0');
//		string* ps222 = new string("3"/*"wepull"*/);
//		string* ps3 = new string[3];


		Stack<char> sc(4);
		sc.push('A');sc.push('B');sc.push('C');sc.push('S');
		show(sc);
		Stack<char> sc2(sc);
		show(sc2);
		Stack<char> sc3;
		sc3 = sc;
		show(sc3);

		Stack<int> si;
		si.push(1);si.push(2);si.push(3);
		show(si);

		Stack<string> ss;
		ss.push("AAA");ss.push("ABC");ss.push("VVV");
		show(ss);
	} catch (const char* e) {
		cout<<"e:"<<e<<endl;
	}

	return 0;
}