Abstract class

An abstract class is a class which provides a common definition of base class that multiple derived classes can share.

Some distinct characteristics of an abstract class:

Ø We cannot create an object of the abstract class, it must be inherited.

Ø It can have abstract as well as non-abstract members in an abstract class.

Ø We must declare at least one abstract method in the abstract class.

Ø An abstract class is always public.

We need abstract classes whenever we define a template that needs to be followed by all the derived classes.

Abstract classes are specified by keyword Abstract

Example:

Abstract class A

{

Public abstract void display ();

}

Class B : A

{

Public override void display ()

{

Console.writeLine (“this is class B’s method”);

}

Class C : A

{

Public override void display ()

{

Console.writeLine (“this is class C’s method”);

}

Class program

{

Public static void main (string [] args)

{

B b=new B ();

b.display ();//calls class B’s method

C c=new C ();

c.display ();// calls class C’s method

}

}