stl_string用法

#include <string>
#include <iostream>
using namespace std;

int main()
{
 string show;
 string show2="aaaa";
 show="bbbb";
 
 cout<<"交换两个字符串的内容"<<endl;
 show.swap(show2);     
 cout<<show<<endl;
 cout<<show2<<endl;
 
 cout<<endl;
 cout<<"测试是否为空"<<endl;  
 cout<<show.empty()<<endl;
 cout<<show<<endl;
 
 cout<<endl;
 cout<<"找集合sset= abcz 中的某个字符在内容words中第一次出现的位置"<<endl;
 string words="abcdefghijklmnopqrstuvwxyz";   
 string sset="bhcz";       
 cout<<words.find_first_of(sset )<<endl;
 cout<<words.find_last_of(sset)<<endl;
 
 cout<<endl;
 cout<<"查找某一个串的位置"<<endl;
 string::size_type fpos =words.find("def");
 if(fpos!= string::npos)
 {
  cout<<fpos<<endl;
 }
 
 
 cout<<endl;
 cout<<"以某个串a替换串b"<<endl;
 string strsrc="a";
 string strdst="bbb";
 string::size_type pos=0;
 string::size_type srclen=strsrc.size();
 string::size_type dstlen=strdst.size();
 while( (pos=words.find(strsrc, pos)) != string::npos)
 {words.replace(pos, srclen, strdst); pos += dstlen;}
 cout<<words<<endl;
 
 words="1234567890";
 cout<<endl;
 cout<<"从索引1开始的2个字符替换成后面的string"<<endl;
 words.replace(1,2,"n ");
 cout<<words<<endl;
 
 cout<<endl;
 cout<<words<<endl;
 cout<<"删除索引从a开始的b个字符串"<<endl;
 words.erase(0,1);
 cout<<words<<endl;
 
 cout<<endl;
 cout<<"输入一行，以' '结尾"<<endl;
 //getline(cin,words,' ');
 cout<<words<<endl;
 
 words="123456";
 cout<<endl;
 cout<<"从索引a开始的b个串"<<endl;
 show=words.substr(1,3);
 cout<<show<<endl;
 
 cout<<endl;
 cout<<"TrimRinght和TrimLeft"<<endl;
 words="  123 456 _ 789   ";
 words.erase(words.find_last_not_of(' ')+1,words.size());
 words.erase(0,words.find_first_not_of(' '));
 cout<<words<<endl;

 words.insert(1,"hello!");
 return 0;
}