rem: start = end = 0; str = 0; return;
add: start = str->find_first_not_of(separator, end); if(start == std::string::npos) { start = end = 0; str = 0; return; }  end = str->find_first_of(separator, start);
context:   void find_next(void)  {    start = str->find_first_not_of(separator, end);    if(start == std::string::npos)    {      start = end = 0;      str = 0;      return;    }    end = str->find_first_of(separator, start);  }