Friends

Lecture 4 - Slide 32 : 40

Friends

A friend of class C has access to private and protected members of C

The C++ Prog. Lang. (3. edition): Page 278-282

The C++ Prog. Lang. (4. edition): Page 571-...

Friendship principles:
- Friendship is provided by the class that encapsulate members with access limitations
  - Friendship cannot be taken by a class or function that wants access
- Friendship can be granted to
  - an ordinary function, or to an overloaded operator
  - a member function in another class
  - all members of another class
- Friendship is not transitive, and it is not inherited

In some cases it is convenient define a function as a friend instead as a member.

Because a friend is activated in another way than a member: f(x,y) versus x.f(y).