Abstract class in C#

Introduction

An Abstract class is a class that provides a common definition to the subclasses and this is the type of class whose object is not created.

Key points of Abstract Classes

• Abstract classes are declared using the abstract keyword.

• We cannot create an object of an abstract class.

• If you want to use it then it must be inherited in a subclass.

• An Abstract class contains both abstract and non-abstract methods.

• The methods inside the abstract class can either have an implementation or no implementation.

• We can inherit two abstract classes; in this case the base class method implementation is optional.

• Methods inside the abstract class cannot be private.

• Abstract classes are useful when you need a class for the purpose of inheritance and polymorphism.

• The purpose of an abstract class is to provide default functionality to its subclasses.

• When a class contains at least one abstract method, then the class must be declared as an abstract class.

• It is mandatory to override the abstract method in the derived class.