use of 'outer variable' in anonymous method : Method Parameter « Class « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Class
3. Method Parameter

using System;
using System.Collections.Generic;
using System.Text;

    class Program
    {
        delegate void MessagePrintDelegate(string msg);

        static void Main(string[] args)
        {
            string source = "Outer";
            MessagePrintDelegate mpd3 = delegate(string msg)
            {
                Console.WriteLine("[{0}] {1}", source, msg);
            };
            LongRunningMethod(mpd3);

        }

        static void LongRunningMethod(MessagePrintDelegate mpd)
        {
            for (int i = 0; i < 99; i++)
            {
                if (i % 25 == 0)
                {
                    mpd(string.Format("Progress Made. {0}% complete.", i));
                }
            }
        }

        static void PrintMessage(string msg)
        {
            Console.WriteLine("[PrintMessage] {0}", msg);
        }
    }