© Ray Lischner 2020
R. LischnerExploring C++20https://doi.org/10.1007/978-1-4842-5961-0_39

39. Virtual Functions

Ray Lischner1 
(1)
Ellicott City, MD, USA
 

Deriving classes is fun, but there’s not a lot you can do with them—at least, not yet. The next step is to see how C++ implements type polymorphism, and this Exploration starts you on that journey.

Type Polymorphism

Recall from Exploration 37 that type polymorphism is the ability of a variable of type B to take the “form” of any class derived from B. The obvious question is “How?” The key in C++ is to use a magic keyword to declare a member function in a base class and also implement the function in a derived class with a different magic word. The magic keyword tells the compiler that you want to ...

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