Are derived classes considered friends?

问题

If I create base class A and A is a friend of class B, can a class derived from A access B to its liking, or else what is it allowed?

Thanks

回答1:

struct A{};

struct Ader : A{};

struct B{
   friend struct A;
};

No. Friendship is not inherited in C++. It is also not transitive.

Ader can not access B as a friend unless explicitly given friendship by B, just because it's base A is a friend of B.

回答2:

No, that's not allowed. Check here.

来源：https://stackoverflow.com/questions/4083838/are-derived-classes-considered-friends