foo.cc: In function 'int main()':
foo.cc:14:75: error: 'C' was not declared in this scope
  cout<<b<<"!"<<b<<"·"<<a<<"!又见到您了，真是太高兴啦……"<<C<<"，对吧?";
                                                                           ^

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