/in/foo.cc: In member function 'void num::init(const string&)':
/in/foo.cc:19:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i = 0; i < str.size(); i++)
                    ~~^~~~~~~~~~~~
/in/foo.cc: In function 'int get_complex(const string&)':
/in/foo.cc:36:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 4; i < str.size()-1; i++)
                  ~~^~~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:73:16: warning: array subscript has type 'char' [-Wchar-subscripts]
     if (table[c]) { flag_err = 1; }
                ^
/in/foo.cc:76:13: warning: array subscript has type 'char' [-Wchar-subscripts]
      table[c] = 1;
             ^