c++ 字符串替换

#include   <string>
#include   <iostream>

using namespace std;

string& replace_all(string &str, const string& old_value,const string& new_value) {
while (true) {
string::size_type pos(0);
if ((pos = str.find(old_value)) != string::npos)
str.replace(pos, old_value.length(), new_value);
else
break;
}
return str;
}

string& replace_all_distinct(string &str, const string& old_value,const string& new_value) {
for (string::size_type pos(0); pos != string::npos; pos
+= new_value.length()) {
if ((pos = str.find(old_value, pos)) != string::npos)
str.replace(pos, old_value.length(), new_value);
else
break;
}
return str;
}

int main() {
    char *str="12\n  59\n" ;
    int pos1,pos2 ;
    sscanf(str,"%d\n %d",&pos1,&pos2) ;
    cout<<"pos1:"<<pos1<<"pos2:"<<pos2<<endl ;
}