virtual function and virtual inheritence

[Vuhelper]

With virtual functions, derived classes can provide new implementations of functions from their base classes. When someone calls a virtual function of an object of the derived class, this new implementation is called, even if the caller uses a pointer to the base class, and doesn't even know about the particular derived class.

Virtual inheritance is a type of inheritance in which the part of the object that belongs to virtual base class becomes common direct base class for derived class and any other class that derives from it. Virtual inheritance is used in multiple inheritance.