例 3.20 string类运算符的操作

//例 3.20 string类运算符的操作。#include<iostream>#include<string>using namespace std;int main(){string s1 = "ABC";  //定义string类对象s1并进行初始化string s2 = "DEF";  //定义string类对象s2并进行初始化string s3("GHI");   //定义string类对象s3并进行初始化string s4,s5;       //定义string类对象s4和s5s4 = s1;            //字符串赋值cout<<"s4 is "<<s4<<endl;s5 = s1+s2;                      //字符串连接cout<<"s1+s2 is "<<s5<<endl;s5 = s1+"123";                   //字符串连接cout<<"s1+\"123\" is "<<s5<<endl;if(s3>s1)                    //字符串比较      cout<<"s3>s1"<<endl;else  cout<<"s3<s1"<<endl; if(s4==s1)                    //字符串比较  cout<<"s4==s1"<<endl;else  cout<<"s4<>s1"<<endl;cout<<"请输入一个字符串给s5:";  cin>>s5;                        //从键盘输入一个字符串给s5cout<<"s5 is "<<s5<<endl;return 0;}