/in/foo.cc: In function 'void td(std::__cxx11::string, std::__cxx11::string)':
/in/foo.cc:8:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<t.length();i++)
          ~^~~~~~~~~~~
/in/foo.cc:23:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(i=0;i<t.length();i++)
          ~^~~~~~~~~~~