Pure Virtual Function in C++ Explained

A pure virtual function in C++ is a function declared in a base class as a pure virtual function, with its implementation carried out in a derived class. The declaration of a pure virtual function involves adding “=0” after the function declaration, like this: virtual void func() = 0;. Pure virtual functions do not have a function body, only a declaration, so they cannot be directly implemented in the base class.

The purpose of pure virtual functions is to define an interface that forces all derived classes to implement this function. This allows for polymorphism, where different derived class objects can implement the same interface, thus increasing the code’s scalability and maintainability. The existence of pure virtual functions makes the base class an abstract class, unable to instantiate objects and can only be used as a base class for derived classes.