using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

​

//use it with polymorphic behaviour

​

//The abstract modifier indicates that the thing being modfied has a missing or incomplete

//implementation. abstract modifier can be used with classes and class members

​

//Use the abstract modifier in a class declaration to indicate thata a class is

//intended only to be a base class of other classes

​

//Members marked as abstract, or included in an abstarct class, must be

//impememted by class that derive from the abstract class

​

public class Program

{

    public static void Main()

    {

        //cannot craete an instance of abstract class

        //var auto = new Automobile();

        var car = new Car();

        car.Drive();

        var feline = new Feline();

    feline.Walk();

    }

}

​

​

abstract class Automobile

{

    public virtual void Drive()

    {

        Console.WriteLine("Driving automobile");

    }

​

}

​

class Car : Automobile

{

​

    public override void Drive()

    {

        Console.WriteLine("Car automobile");

    }

​

​

}

​

abstract class Animal

{

​

    public abstract void Walk();

​

}

​

class Feline : Animal

{

​

    public override void Walk()

    {

        Console.WriteLine("Feline pouncing");

    }

​

​

}

​