字符串類

#define _CRT_SECURE_NO_WARNINGSss

#include <iostream>
using namespace std;

class String
{
private:
	char* _ptr;
public:
	String()//構造函數
		:_ptr(new char[1])
	{
		_ptr[0] = '\0';
	}
	String(char* str)//構造函數重載
		:_ptr(new char[strlen(str)+1])
	{
		strcpy(_ptr,str);
	}
	String(const String& s)//拷貝構造
		:_ptr(new char[strlen(s._ptr)+1])
	{
		strcpy(_ptr,s._ptr);
	}
	String& operator=(const String& s)//賦值操作符的重載
	{
		if (this != &s)
		{
			_ptr = s._ptr;
		}
		return *this;
	}
	~String()//析構函數
	{
		if (_ptr != NULL)
		{
			delete[] _ptr;
			_ptr = NULL;
		}
	}
public:
	char* Getstr()
	{
		return _ptr;
	}
	char& operator[](size_t index)
	{
		return _ptr[index];
	}
};

int main()
{
	String s1;
	cout<<"s1:"<<s1.Getstr()<<endl;

	String s2("abcd");
	cout << "s2:" << s2.Getstr() << endl;

	String s3(s2);
	cout << "s3:" << s3.Getstr() << endl;

	s1 = s3;
	cout << "s1:" << s1.Getstr() << endl;

	system("pause");
	return 0;
}