foo.cc: In function 'int main()':
foo.cc:7:18: 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>; std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::size_type = long unsigned int]' (did you forget the '()' ?)
    7 |  for(int i=0;i<a.size;i++){
      |                ~~^~~~
      |                      ()

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