C++实现一个自己的string类

程序

#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;
class String{
private:
    char*buffer;
    int len;
public:
    String(){
        len=0;
        buffer=new char[len+1];
      //  buffer[0]='\0';

    }
    String(const char*str){
        len=strlen(str);
      //  cout<<"the length is "<<len<<endl;
        buffer=new char[len+1];
        memcpy(buffer,str,len);
        buffer[len]='\0';
    }
    String(const String&other){
        len=other.len;
        buffer=new char[len+1];
        memcpy(buffer,other.buffer,len+1);
    }
    ~String(){delete [] buffer;}
    const char*c_str() const{return buffer;}
    int size() const{return len;}

};
int main(){
    String str1;
    cout<<"str1: "<<str1.c_str()<<" , size = "<<str1.size()<<endl;
    const char*str2="hello world";
    String str3(str2);
    cout<<"str3: "<<str3.c_str()<<" , size = "<<str3.size()<<endl;
    String str4(str3);
    cout<<"str4: "<<str4.c_str()<<" , size = "<<str4.size()<<endl;
    return 0;
}

测试结果