An abstract class is a class that is declared abstract and cannot be instantiated but can be subclassed. Abstract classes may or may not include abstract methods and allow for data and control abstraction by abstracting data members and functions that perform operations. The sample code demonstrates how to define and subclass an abstract class.

1. Abstract Classes
● An abstract class is a class that is declared
abstract.
● It may or may not include abstract methods.
● Abstract classes cannot be instantiated, but
they can be subclassed.
Syntax:
abstract class <class-name>{}

2. Types of abstraction
● Data abstraction
Abstracting the data members in the abstract
class
● Control abstraction
Abstracting the functions that performs the
operation.

3. Sample code for abstract classes

4. Sample output