foo.cc: In member function ‘BigInt BigInt::operator+(const BigInt&) const’:
foo.cc:52:21: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   52 | if (count == 0 && i >= s.size() && i >= b.s.size()) break;
      |                   ~~^~~~~~~~~~~
foo.cc:52:38: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   52 | if (count == 0 && i >= s.size() && i >= b.s.size()) break;
      |                                    ~~^~~~~~~~~~~~~
foo.cc:54:7: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   54 | if (i < s.size()) x += s[i];
      |     ~~^~~~~~~~~~
foo.cc:55:7: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   55 | if (i < b.s.size()) x += b.s[i];
      |     ~~^~~~~~~~~~~~
foo.cc: In member function ‘BigInt BigInt::operator*(int) const’:
foo.cc:67:21: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   67 | if (carry == 0 && i >= s.size()) break;
      |                   ~~^~~~~~~~~~~
foo.cc:69:7: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   69 | if (i < s.size()) x += (long long)times * s[i];
      |     ~~^~~~~~~~~~
foo.cc: In function ‘std::ostream& operator<<(std::ostream&, const BigInt&)’:
foo.cc:83:19: warning: comparison of integer expressions of different signedness: ‘int’ and ‘size_t’ {aka ‘long unsigned int’} [-Wsign-compare]
   83 | for (int j = 0; j < strlen(buf); j++) out << buf[j];
      |                 ~~^~~~~~~~~~~~~
foo.cc: In function ‘bool check(std::string&, std::string&, int, int)’:
foo.cc:166:35: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  166 | for (int i = 0, j = pos + blank;i < a.size() && j < b.size(); i++,j++)
      |                                 ~~^~~~~~~~~~
foo.cc:166:51: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  166 | for (int i = 0, j = pos + blank;i < a.size() && j < b.size(); i++,j++)
      |                                                 ~~^~~~~~~~~~
foo.cc: In function ‘bool check_through(std::string, std::string&, int)’:
foo.cc:175:11: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  175 | for (;pos < b.size(); pos += a.size())
      |       ~~~~^~~~~~~~~~
foo.cc: In function ‘bool all(std::string&, char)’:
foo.cc:185:19: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  185 | for (int i = 0; i < a.size(); i++)
      |                 ~~^~~~~~~~~~
foo.cc: In function ‘int main()’:
foo.cc:198:28: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
  198 | else for (int len = 1; len <= s.size(); len++)
      |                        ~~~~^~~~~~~~~~~