/in/foo.cc: In function 'bool ifstr(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:8:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < b.size(); )
                    ^
/in/foo.cc:11:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (; j < a.size(); j++)
            ^