foo.cc: In function ‘void init(std::string, int*)’:
foo.cc:7:24: 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=1;i <= s.size();i++)
      |                      ~~^~~~~~~~~~~