using System;

public abstract class BaseClass   // Abstract BASE class

{

    //fields and properties

    protected int _x = 100;  //has a value //highlight a different with interfaces

    protected int _y = 150;

    public abstract int X    { get; }  //abstract in a member -> you're like an interface

    public abstract int Y    { get; }

    //methods

    public abstract void AbstractMethod();   // Abstract method is only defined (NOT IMPLEMENTED) [Looks a lot like an interface!]

}

​

//children class

public class DerivedClass : BaseClass

{

    public override void AbstractMethod() // overriding the method  //need to use the override if 'abstract' is in the fields/properties/methods

    {

        _x++;

        _y++;

    }

    public override int X   // overriding property

    {

        get

        {

            return _x + 10;

        }

    }

    public override int Y   // overriding property

    {

        get

        {

            return _y + 10;

        }

    }

    public static void Main()

    {

        DerivedClass o = new DerivedClass();

        o.AbstractMethod();

        Console.WriteLine("x = {0}, y = {1}", o.X, o.Y);

    }

}

// Output: x = 111, y = 161