foo.cc: In function 'void std::writef(double, int)':
foo.cc:65:24: warning: array subscript has type 'char' [-Wchar-subscripts]
      while (x) s_[++top] = x % 10, x /= 10;
                        ^
foo.cc:66:34: warning: array subscript has type 'char' [-Wchar-subscripts]
      while (top) *p3++ = s_[top--] ^ '0';
                                  ^
foo.cc: In function 'void std::write(Tp)':
foo.cc:92:24: warning: array subscript has type 'char' [-Wchar-subscripts]
      while (x) s_[++top] = x % 10, x /= 10;
                        ^
foo.cc:93:34: warning: array subscript has type 'char' [-Wchar-subscripts]
      while (top) *p3++ = s_[top--] ^ '0';
                                  ^

自豪的采用 HydroJudge 进行评测(github.com/hydro-dev/HydroJudge)

{"receive":"2020-07-21T03:16:34.535Z","handle":"2020-07-21T03:16:34.535Z","cache_start":"2020-07-21T03:16:34.542Z","read_cases":"2020-07-21T03:16:34.660Z","judge":"2020-07-21T03:16:34.660Z","done":"2020-07-21T03:16:35.950Z"}