/in/foo.cc: In function 'std::string subtractStrings(std::string, std::string)':
/in/foo.cc:12:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |     while (i < num1.size() || i < num2.size()) {
      |            ~~^~~~~~~~~~~~~
/in/foo.cc:12:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   12 |     while (i < num1.size() || i < num2.size()) {
      |                               ~~^~~~~~~~~~~~~
/in/foo.cc:13:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   13 |         int digit1 = i < num1.size() ? (num1[i] - '0') : 0;
      |                      ~~^~~~~~~~~~~~~
/in/foo.cc:14:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         int digit2 = i < num2.size() ? (num2[i] - '0') : 0;
      |                      ~~^~~~~~~~~~~~~