A base class is a type of class that is used to inherit member variables and methods from.

Or: a base class is the entity that all derived classes share.

The code below shows how an Animal is used as a base class and Cat and Dog are derived classes (of Animal).


#include <iostream>



struct Animal //Animal is a (non-abstract) base class

{

  virtual void MakeSound() = 0;

  //All base classes must have a virtual destructor

  // (Herb Sutter & Andrei Alexandrescu, 2004)

  virtual ~Animal() {}

};



//A cat is a-kind-of animal.

//Cat will not be used as a base class,

//therefore it has no virtual destructor

struct Cat : public Animal 

{

  void MakeSound() const { std::cout << "Meow" << std::endl; }

};



//A dog is a-kind-of animal.

//Dog will not be used as a base class,

//therefore it has no virtual destructor

struct Dog : public Animal

{

  void MakeSound() const { std::cout << "Bark" << std::endl; }

};

A special type of base class is the abstract base class.

All base classes must have a (public) virtual destructor. A non-base class must have a (non-public) non-virtual destructor [1].

References

Herb Sutter, Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Item 50: 'Make base class destructors public and virtual, or protected and nonvirtual'.

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

(C++) Base class

References