using System;

public class Program

{

    public static void Main()

    {

        Func<int,int,int> sum = (a,b)=>{        

            return a+ 10 + b;

        };

        Console.WriteLine(sum(12,2).ToString());

    }

}

​

public class Parent

{

    delegate void NumberChanger(ref int n);

    private int parentVar = 100;

    Child ChildInstance = new Child();

    public void Display(){

        NumberChanger nc1 = new NumberChanger(ChildInstance.Display);   

        Console.WriteLine("child var :{0}",ChildInstance.childVar);

        nc1(ref parentVar);

        Console.WriteLine("child var :{0}",parentVar);

    }

}

​

​

public class Child

{

   public int childVar = 10;

    public void Display(ref int a){         

          Parent ParentInstance = new Parent();

          Console.WriteLine("parent var :{0}",a);

          a++;

    }

}