Abstract-Classes

using System;

public abstract class Animal
{
    public abstract string GetName();
    abstract public int Speed { get; }
}



using System;

public class Cheetah : Animal
{
    public override int Speed
    {
        get
        {
            return 100;
        }
    }

    public override string GetName()
    {
        return "cheetah";
    }
}


using System;

public class Turtle : Animal
{
    public override int Speed
    {
        get
        {
            return 1;
        }
    }

    public override string GetName()
    {
        return "turtle";
    }
}


using System;

class AbstractClasses
{
    static void Main()
    {
        Turtle turtle = new Turtle();
        Console.WriteLine("The {0} can go {1} km/h ",
            turtle.GetName(), turtle.Speed);
        Cheetah cheetah = new Cheetah();
        Console.WriteLine("The {0} can go {1} km/h ",
            cheetah.GetName(), cheetah.Speed);

        System.Collections.Generic.List<int> l;
        System.DateTime dt;
    }
}


OUTPUT

The turtle can go 1 km/h

The cheetah can go 100 km/h