foo.cc: In function ‘int main()’:
foo.cc:12:33: error: invalid use of member function ‘std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size() const [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>; size_type = long unsigned int]’ (did you forget the ‘()’ ?)
   12 |                 for(int i=0;i<s.size;i++)
      |                               ~~^~~~
      |                                     ()