Why can't I access a protected member from an instance of a derived class?

Question

I haven\'t done C++ in a while and can\'t figure out why following doesn\'t work:

class A {
protected:
  int num;
};

class B : public A {
};

main () {
  B          


        

Answer 1

"Protected" means protected from access outside of a member function, or a member function of a derived class. The "main" function isn't a member of either class, but it's trying to directly access the member variable.