Friend Declarations

The friend declaration appears in a class body and grants a function or another class access to private and protected members of the class where the friend declaration appears. Friends have access to all members of a class.

A class can declare friendship to a function, a method, or a class.

Rules:

1. The declaration of a friendship can be anywhere.
2. The access specifier of the friendship declaration is not relevant.
3. Friendship cannot be inherited (your friend’s children are not your friends).
4. Friendship is not transitive (a friend of your friend is not your friend).

Access specifiers have no effect on the meaning of friend declarations (they can appear in private: or in public: sections, with no differences).

A friend has full control of the internals of a class.