1.使用string的find_first_not_of,和find_last_not_of方法

 

1 #include 
     
       2 #include 
      
        3  4 std::string& trim(std::string &); 5  6 int main()  7 { 8     std::string s = " Hello World!! "; 9     std::cout << s << " size:" << s.size() << std::endl;10     std::cout << trim(s) << " size:" << trim(s).size() << std::endl;11 12     return 0;13 }14 15 std::string& trim(std::string &s) 16 {17     if (s.empty()) 18     {19         return s;20     }21 22     s.erase(0,s.find_first_not_of(" "));23     s.erase(s.find_last_not_of(" ") + 1);24     return s;25 }