Inheriting Concrete virtual Functions

In our Employee case study, each concrete class provides its own implementation for virtual functions earnings and print. You’ve learned that each class which inherits directly from abstract base class Employee must implement earnings in order to be a concrete class, because earnings is a pure virtual function. These classes do not need to implement function print, however, to be considered concrete—print is not a pure virtual function and derived classes can inherit class Employee’s implementation of print. Furthermore, class BasePlusCommissionEmployee does not have to implement either function print or earnings—both function implementations can be inherited from concrete class CommissionEmployee. If a class in our hierarchy were to inherit function implementations in this manner, the vtable pointers for these functions would simply point to the function implementation that was being inherited. For example, if BasePlusCommissionEmployee did not override earnings, the earnings function pointer in the vtable for class BasePlusCommissionEmployee would point to the same earnings function as the vtable for class CommissionEmployee points to.