Virtual Functions Pure Virtual Functions Abstract Classes In C

Virtual Functions Pure Virtual Functions Abstract Classes A pure virtual function (or abstract function) in c is a virtual function for which we can have an implementation, but we must override that function in the derived class, otherwise, the derived class will also become an abstract class. a pure virtual function is declared by assigning 0 in the declaration. example of pure virtual functions. c . Pure virtual (abstract) functions and abstract base classes. so far, all of the virtual functions we have written have a body (a definition). however, c allows you to create a special kind of virtual function called a pure virtual function (or abstract function) that has no body at all! a pure virtual function simply acts as a placeholder.

Mastering Virtual Functions Pure Virtual Functions And Abstract A pure virtual function or pure virtual method is a virtual function that is required to be implemented by a derived class if the derived class is not abstract. when a pure virtual method exists, the class is "abstract" and can not be instantiated on its own. instead, a derived class that implements the pure virtual method(s) must be used. A virtual function is a member function of base class which can be redefined by derived class. a pure virtual function is a member function of base class whose only declaration is provided in base class and should be defined in derived class otherwise derived class also becomes abstract. classes having virtual functions are not abstract. Having a pure virtual function in a superclass does not prevent function chaining. the employee calc pay function is a pure virtual function, making the function and the employee class abstract. we calculate the pay for employees that receive a salary by taking their annual salary and dividing it by the number of pay periods. Abstract class. a class that contains a pure virtual function is known as an abstract class. in the above example, the class shape is an abstract class. we cannot create objects of an abstract class. however, we can derive classes from them, and use their data members and member functions (except pure virtual functions).