c++ string去除首尾 空格、\n、\r、\t

    string s = "    test ";
    size_t n = s.find_last_not_of(" \r\n\t");
    if (n != string::npos){
        s.erase(n + , s.size() - n);
    }
    n = s.find_first_not_of(" \r\n\t");
    if (n != string::npos){
        s.erase(, n);
    }

string trimstr(string s){
  size_t n = s.find_last_not_of(" \r\n\t");
    if (n != string::npos){
        s.erase(n + , s.size() - n);
    }
    n = s.find_first_not_of(" \r\n\t");
    if (n != string::npos){
        s.erase(, n);
    }
    return s;
}