/in/foo.cc: In member function 'BigInt BigInt::operator+(const BigInt&) const':
/in/foo.cc:33:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i(0), c(0); c != 0 || i < num.size() || i < b.num.size(); ++i)
                                        ~~^~~~~~~~~~~~
/in/foo.cc:33:60: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i(0), c(0); c != 0 || i < num.size() || i < b.num.size(); ++i)
                                                          ~~^~~~~~~~~~~~~~
/in/foo.cc:36:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < num.size()) x += num[i];
                 ~~^~~~~~~~~~~~
/in/foo.cc:37:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < b.num.size()) x += b.num[i];
                 ~~^~~~~~~~~~~~~~
/in/foo.cc: In member function 'BigInt BigInt::operator-(const BigInt&) const':
/in/foo.cc:49:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i(0), c(0); c != 0 || i < num.size() || i < b.num.size(); ++i)
                                        ~~^~~~~~~~~~~~
/in/foo.cc:49:60: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i(0), c(0); c != 0 || i < num.size() || i < b.num.size(); ++i)
                                                          ~~^~~~~~~~~~~~~~
/in/foo.cc:52:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < num.size()) x += num[i]; else break;
                 ~~^~~~~~~~~~~~
/in/foo.cc:53:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             if (i < b.num.size()) x -= b.num[i];
                 ~~^~~~~~~~~~~~~~