What are the common methods of string class in C++

 
#include<cstdio>
#include<iostream>
#include<string>
using namespace std;
int main()
{
    string str1 = "hello";
 
    int length = str1.length();
    printf("调用str.length()函数获取字符串长度：%d\n\n",length );
    return 0;
}

 
#include<cstdio>
#include<iostream>
#include<string>
using namespace std;
int main()
{
    string str1 = "hello";
    string str2="my girl!";
    string str3="hello ";
 
    string str4=str1+str2;
    string str5=str3+str2;
    cout<<"字符串str1+str2连接结果："<<str4<<endl;
    cout<<endl;
    cout<<"字符串str3+str2连接结果："<<str5<<endl;
    return 0;
}

 
#include<cstdio>
#include<iostream>
#include<string>
using namespace std;
int main()
{
    string str1 = "hello";
    string str2="my girl!";
    string str3="hello ";
 
    if (str1 < str3)
        cout << "字符串比较结果：" << "str1<str2" << endl;
    cout << endl;
    return 0;
}

 
#include<cstdio>
#include<iostream>
#include<string>
#include<cstring>
using namespace std;
int main()
{
    string str1 = "hello";
    string str2="my girl!";
    string str3="hello ";
 
    char *d = new char[20];  //因为下一句那里不是直接赋值，所以指针类型可以不用const char *
    strcpy(d, str3.c_str());  //c_str 取得C风格的const char* 字符串
    cout << "str3:" << c << endl;
    cout << "d:" << d << endl;
    str3 = "hahaha";
    cout << "str3:" << c << endl;
    cout << "d:" << d << endl;
    return 0;
}