Abstraction

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace HelloWorld
{
// abstract class we can't create instance for that.
abstract class Animal{

public abstract void Sound();
// normal function inside the abstract class function
public void fun(){
Console.WriteLine(":-- Normal function");
}

}

class Pig:Animal // inhert the parent class.
{
public override void Sound()
{
Console.WriteLine(":-- Overridden function");
}

}
public class Program
{
public static void Main(string[] args)
{

		var obj = new Pig(); // Create object of the child class to access the parent properties.
	obj.Sound();
	obj.fun();
	} 
}

}

// another Example

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace HelloWorld
{
public abstract class Fruits{
public abstract void Sweets();
public abstract void Sour();

}

class Teste: Fruits {

public override void Sweets()
{
Console.WriteLine("Fruits are Sweets");
}
public override void Sour(){
Console.WriteLine("Fruits are Sour");
}

}
public class Program
{
public static void Main(string[] args)
{
Teste obj = new Teste();
obj.Sweets();
obj.Sour();
}
}
}