/in/foo.cc: In function 'int main()':
/in/foo.cc:8:11: error: could not convert 'huida.std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=<char, std::char_traits<char>, std::allocator<char> >(koulin)' from 'std::__cxx11::basic_string<char>' to 'bool'
  if (huida=koulin) cout<<"门打开了";
      ~~~~~^~~~~~~