foo.cc: In function ‘void GetNext(std::string, int*)’:
foo.cc:8:18: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
    8 |         while (j < t.length() - 1)
      |                ~~^~~~~~~~~~~~~~~~
foo.cc: In function ‘int KMP(std::string, std::string)’:
foo.cc:26:18: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   26 |         while (i < s.length() && j < t.length())
      |                ~~^~~~~~~~~~~~
foo.cc:26:36: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   26 |         while (i < s.length() && j < t.length())
      |                                  ~~^~~~~~~~~~~~
foo.cc:39:16: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   39 |         if (j  >= t.length())
      |             ~~~^~~~~~~~~~~~~