using System;

​

public class Program

{

    // declare the delegate - notice the parameter 'double x'

    //      delegate parameters must match the methods they are delegates for

    delegate double DoubleOp(double x);

    public static void Main()

    {

        // create delegate that points to the MultiplyByTwo method

        DoubleOp multiply = MathOperations.MultiplyByTwo;

        // call the MultiplyByTwo method using the delgate

        Console.WriteLine("Calling the Multiply method through a delegate: {0}", multiply(2.0));

        // create delegate that points to the Square method

        DoubleOp square = MathOperations.Square;

        // call the Square method using the delegate

        Console.WriteLine("Calling the Square method through a delegate: {0}",square(3.0));

    }

    static void ProcessAndDisplayNumber(DoubleOp action, double value)

    {

      double result = action(value);

      Console.WriteLine(

         "Value is {0}, result of operation is {1}", value, result);

    }

}

​

public static class MathOperations

{

    public static double MultiplyByTwo(double value)

    {

        return value * 2;

    }

    public static double Square(double value)

    {

        return value * value;

    }

}