/in/foo.cc: In function 'std::string TRUN(const string&)':
/in/foo.cc:7:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    7 |  for (int i = 0; i < str.length(); ++i) {
      |                  ~~^~~~~~~~~~~~~~