and implementation inheritance. In both forms of inheritance, a derived class can share or override behavior inherited from a base class. However, use type inheritance only when it is necessary for a derived class to inherit type information as well. The primary reason to inherit type information is to allow for polymorphism.
Express type inheritance by deriving a class from a public base class; express implementation inheritance by deriving a class from a private or protected base class. Strict guidelines for choosing the correct form of inheritance are described in this section.