【C++】模拟string类的实现(string 类的深拷贝)

#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
class String
{
public:
	String()
		:_pstr(new char[1])
	{
		_pstr[0] = '\0';
	}
	String(char *pstr)
		:_pstr(new char[strlen(pstr) + 1])
	{
		strcpy(_pstr, pstr);
	}
	~String()
	{
		if (_pstr)
		{
			delete[] _pstr;
		}
	}
	String(const String &S)
		:_pstr (new char[strlen(S._pstr) + 1])
	{
		strcpy(_pstr, S._pstr);
	}
	String&operator=(const String &S)
	{
		if (this != &S)
		{
			delete []_pstr;
			_pstr = new char[strlen(S._pstr) + 1];
			strcpy(_pstr, S._pstr);
		}
		return *this;
	}
	//优化写法
	/*void Swap(String &s)
	{
		char *tmp = _pstr;
		_pstr = s._pstr;
		s._pstr = tmp;
	}
	String(const String &s) :_pstr(NULL)
	{
		String tmp(s._pstr);
		Swap(tmp);
	}*/
	/*String&operator=(const String &s)
	{
		if (this != &s)
		{
			String tmp(s._pstr);
			Swap(tmp);
		}
		return *this;
	}*/
	//优化赋值运算符重载
	/*void Swap(String s)
	{
		char *tmp = _pstr;
		_pstr = s._pstr;
		s._pstr = tmp;
	}
	String &operator=(const String &s)
	{
		Swap(s);
		return *this;
	}*/
	void GetStr()
	{
		cout << _pstr << endl;
	}
private:
	char *_pstr;
};
int main()
{
	String op1("abcdef");
	op1.GetStr();
	String op2 = op1;
	op2.GetStr();
	String op3;
	op3 = op1;
	op3.GetStr();
	system("pause");
	return 0;
}