using System;

public class Program

{

    delegate void operations(double x);

    public static void Main()

    {

        // Action<T> is a built in delegate

        // point operations to MultiplyByTwo

        // point operations to Square

        operations opr=MathOperations.MultiplyByTwo;

        opr+=MathOperations.Square;

        opr(2.0);

        opr.Invoke(4.0);

        ProcessAndDisplayNumber( 2.0);

        ProcessAndDisplayNumber( 7.94);

        ProcessAndDisplayNumber( 1.414);

        Console.WriteLine();

    }

    static void ProcessAndDisplayNumber( double value)

    {

        Console.WriteLine();

        Console.WriteLine("ProcessAndDisplayNumber called with value = {0}", value);

    }

}

​

class MathOperations

{

    public static void MultiplyByTwo(double value)

    {

        double result = value * 2;

        Console.WriteLine("Multiplying by 2: {0} gives {1}", value, result);

    }

    public static void Square(double value)

    {

        double result = value * value;

        Console.WriteLine("Squaring: {0} gives {1}", value, result);

    }

}