C++ In a Nutshell

Name

private access specifier — Restricts member access to the class

Synopsis

               access-specifier := private

The private keyword can be used within a class definition (followed by a colon) to mark subsequent member declarations as private or before a base-class name in the class header to mark the inheritance as private. The default access level of a class is private, both for members and base classes.

Private members can be used by the class itself or by friends.

Private inheritance means all public and protected members in the base class are private to the derived class.

Example

class rational {public:
  rational(int n, int d) : num_(n), den_(d) { reduce(  ); }
  rational(  ) : num_(0), den_(1) {}
  int num(  ) const { return num_; }
  int den(  ) const { return den_; }
protected:
  void reduce(  ); // Reduce num_ and den_ by gcd.
private:
  int num_, den_;
};
class derived : public rational {};
class myrational : private rational {
public:
  using rational::num;
  using rational::den;
};

See Also

class, protected, public, struct, Chapter 6