Why Use a Pure Virtual Destructor in C ?

Why a Pure Virtual Destructor is Necessary in C

Virtual destructors are crucial in C 's object-oriented programming, but why do we specifically use pure virtual destructors?

When to Use a Pure Virtual Destructor

In general, pure virtual destructors are not a common requirement. However, there are two primary reasons for their existence:

1. Prohibiting Instantiation: When a class is intended to be solely abstract, making its destructor pure virtual prevents its instantiation. This ensures that the class cannot be used to create objects directly, forcing derived classes to provide their own implementation.
2. Reminder for Derived Class Cleanup: If a base class's methods have default implementations and are intended to be overriden in derived classes, the pure virtual destructor serves as a reminder to provide cleanup code in derived classes.

Why Not Use Pure Virtual Member Functions for Abstraction?

While it's true that you can make a class abstract by defining any member function as pure virtual, a pure virtual destructor is unique in that it ensures that all derived classes implement their own cleanup code. This is unlike pure virtual member functions, where derived classes can choose to override specific methods but not others.

Common Practice for Abstract Classes

It's not a good practice to make the destructor of an abstract class pure virtual. A plain virtual destructor is sufficient to prevent instantiation, leaving the decision of providing a custom destructor implementation to the derived classes.

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