The minimum implementation of a delegate

   

/*
C# Programming Tips & Techniques
by Charles Wright, Kris Jamsa

Publisher: Osborne/McGraw-Hill (December 28, 2001)
ISBN: 0072193794
*/
//  Delegate.cs - Demonstrates the minimum implementation of a delegate
//                Compile this program with the following command line:
//                    C:>csc Delegate.cs
//
namespace nsDelegate
{
    using System;

    public class Delegate21
    {
//  Declare the delegate type
        public delegate double MathHandler (double val);
//  Declare the variable that will hold the delegate
        public MathHandler DoMath;

        static public void Main ()
        {
            double val = 31.2;
            double result;
            Delegate21 main = new Delegate21();
//  Create the first delegate
            main.DoMath = new Delegate21.MathHandler (main.Square);
//  Call the function through the delegate
            result = main.DoMath (val);
            Console.WriteLine ("The square of {0,0:F1} is {1,0:F3}",
                                val,  result);
//  Create the second delegate
            main.DoMath = new Delegate21.MathHandler (main.SquareRoot);
//  Call the function through the delegate
            result = main.DoMath (val);
            Console.WriteLine ("The square root of {0,0:F1} is {1,0:F3}",
                               val, result);
        }
        public double Square (double val)
        {
            return (val * val);
        }
        public double SquareRoot (double val)
        {
            return (Math.Sqrt (val));
        }
    }
}