What is the purpose of a pure virtual function in C++?

The purpose of a pure virtual function in C++ is to provide a base class interface that must be implemented by any derived classes.

Here's a step-by-step explanation:

1. Interface Definition: A pure virtual function is used when the base class wants to define a function prototype to be used by derived classes, but it cannot provide a meaningful implementation itself. This is often the case when the base class is abstract in nature.

2. Forcing Overriding: A pure virtual function must be overridden in any non-abstract class that directly or indirectly inherits from the class where the pure virtual function was declared. This ensures that every derived class provides its own version of the function.

3. Creating Abstract Classes: In C++, a class that contains at least one pure virtual function is considered an abstract class. Abstract classes cannot be instantiated, they can only be used as base classes for other classes.

4. Polymorphism: Pure virtual functions are a key part of the "polymorphism" feature in C++. They allow you to call a method on a base class and have it resolved to the correct derived class's method at runtime