stl：find _first_of与search用法

#include<iostream>  
#include<string>  
#include<algorithm>  
using namespace std;  
  
  
int main()  
{  
  
string str("i love you");  
string str1 = "youf";  
  
string::iterator ix = search(str.begin(), str.end(), str1.begin(), str1.end());  
  
if (ix == str.end())  
cout << "connot find it" << endl;  
else  
cout << ix-str.begin();  
  
    int n=str.find_first_of("sdaadosf");  
    cout << n << endl;  
}