Data access privileges

class ClassName {
public:
members with no access restriction
protected:
access by: this, derived classes, friends
private:
access by: this, friends
} ;

• a derived class is a class which inherits from this (see inheritance below)
• a function can be declared friend of a class to be able to access its protected and private data

  class TheClass {
  ...
  friend void theFriendMethod(void);
  };