using System;

public delegate void ItemFoundCallback(int index);

public static class ItemFinder {

    public static void FindItem(string[] list, string stringToFind,

    ItemFoundCallback callback) {

        callback = Program.Announce;

        for(int counter=0;counter<list.Length;counter++)

        {

            if (list[counter] == stringToFind)

                callback(counter);

        }

​

    }

}

public class Program

{

    public static void Announce(int i) {

        Console.WriteLine("String found at index {0}!",i);

    }

    public static void Main()

    {

        string[] s = {"Pikachu", "Squirtle", "Ditto",

                      "Pikachu", "Ditto", "Dragonite"};

        Console.WriteLine("Finding Pikachu...");

        ItemFinder.FindItem(s,"Pikachu",Announce);

        Console.WriteLine("Finding Ditto...");

        ItemFinder.FindItem(s,"Ditto",Announce);

    }

}

​