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C++ Abstract Classes

Abstract Classes

C++ abstract classes use pure virtual functions.

What are Abstract Classes?

In C++, an abstract class is a class that cannot be instantiated directly. It is designed to be a base class that other classes can derive from. An abstract class is characterized by the presence of at least one pure virtual function. A pure virtual function is declared by assigning 0 in its declaration.

Purpose of Abstract Classes

Abstract classes serve as a blueprint for other classes. They allow you to define a common interface that derived classes must implement. This ensures a consistent API and allows polymorphic behavior.

Defining and Using Pure Virtual Functions

A pure virtual function in C++ is a virtual function that is declared by using the syntax = 0. This means that the function does not have an implementation in the abstract class, and it must be overridden in any derived class that is not also abstract.

Example of Abstract Class Usage

Consider a scenario where you have a base class Shape with a pure virtual function draw(). Derived classes Circle and Square must implement this function.

Benefits of Using Abstract Classes

Abstract classes provide several benefits:

  • Encapsulation of common behavior in base classes.
  • Enforcement of a consistent interface across all derived classes.
  • Facilitation of polymorphic behavior, allowing for flexible and reusable code.

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