Accessibility of derived classes to base class conversions

The accessibility of a transformation from a derived class to a base class depends on the access designator specified in the derived list of the derived class. to determine whether conversions to the base class are accessible, consider whether the public members of the base class can be accessed, and if so, the conversion is Accessible, otherwise, the conversion is inaccessible.

• In the case of public inheritance, both user code and descendant classes can use the transformation of the derived class to the base class;
• In the case of private or protected inheritance, the user code cannot convert the derived object class to the base class object;
• Note: If protected is inherited, members of subsequent derived classes can be converted to base class types.

Accessibility of derived classes to base class conversions