Abstract class definition with example in C#.Net

Abstract Class 

Using Abstract keyword, we can create a class using C#.net. Main purpose of the Abstract class is for inheritance for defining the features of the non abstract and derived classes.

Syntax:

public abstract class IAmAbstract
{
//we will write class members here. 
}

Important points:

• An abstract class can't be instantiated. 
• Main purpose of the abstract class is to provide the common definition of the parent class to the multiple child classes. 
• Abstract classes can have the abstract methods. Abstract methods don't have implementation. So, when ever we extend abstract class we have to implement this abstract method. 
• When Abstract class is having the virtual method, still we want to use same method we can override the method.

Example Program:

// compile with: /target:library
public class ClassA
{
    public virtual void Work(int i)
    {
        // Original implementation.
    }
}

public abstract class ClassB : ClassA
{
    public abstract override void Work(int i);
}

public class ClassC : ClassB 
{
    public override void DoWork(int i)
    {
        // New implementation.
    }
}

See more OOPS dotnet Interview Questions
See more ASP.NET, C#.NET, Sql Server Interview Questions