Listing 2: The ScrabbleWord, Dictionary, and yield return (in bold) code.

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

namespace UsingYield
{
  class Program
  {
    static void Main(string[] args)
    {
      Dictionary d = Dictionary.Create();

      //foreach(ScrabbleWord word in d)
      foreach(ScrabbleWord word in 
      d.Get(@"^A\w+E$"))
        Console.WriteLine(word);

      Console.WriteLine("enter");
      Console.ReadLine();
    }

    public class Dictionary : List<ScrabbleWord>
    {
      public void Add(string word, 
      string description, int points)
      {
        this.Add(new ScrabbleWord(word, 
        description, points));
      }

      public static Dictionary Create()
      {
        Dictionary dic = new Dictionary();
        dic.Add("AWE", "three letter word", 6); 
        dic.Add("AWL", "three letter word", 5); 
        dic.Add("AWN", "three letter word", 5); 
        dic.Add("AXE", "three letter word", 2); 
        dic.Add("AYE", "three letter word", 6); 
        dic.Add("AYS", "three letter word", 5); 
        dic.Add("AZO", "three letter word", 12);
        dic.Add("BAA", "three letter word", 4); 
        dic.Add("BAD", "three letter word", 4); 
        dic.Add("BAG", "three letter word", 4); 
        dic.Add("BAH", "three letter word", 4); 
        dic.Add("BAL", "three letter word", 4); 
        dic.Add("BAM", "three letter word", 4); 
        dic.Add("BAN", "three letter word", 4); 
        dic.Add("BAP", "three letter word", 4); 
        dic.Add("BAR", "three letter word", 4); 
        dic.Add("BAS", "three letter word", 4); 
        dic.Add("BAT", "three letter word", 4); 
        dic.Add("BAY", "three letter word", 7); 
        dic.Add("BED", "three letter word", 4); 
        dic.Add("BEE", "three letter word", 5); 
        dic.Add("BEG", "three letter word", 4); 
        dic.Add("BEL", "three letter word", 4); 
        dic.Add("BEN", "three letter word", 4); 
        dic.Add("BET", "three letter word", 4); 
 
        return dic;
      }

      public IEnumerable<ScrabbleWord> Get(
      string regex)
      {
        foreach(ScrabbleWord o in this)
          if(Regex.IsMatch(o.Word, regex))
            yield return o;
      }
    }

    public class ScrabbleWord
    {
      private string word;
      public string Word
      {
      	get
      	{
      		return word;
      	}
      	set
      	{
      		word = value;
      	}
      }

      private string description;
      public string Description
      {
      	get
      	{
      		return description;
      	}
      	set
      	{
      		description = value;
      	}
      }

      private int points;
      public int Points
      {
      	get
      	{
      		return points;
      	}
      	set
      	{
      		points = value;
      	}
      }

      /// <summary>
      /// Initializes a new instance of 
      /// the ScrabbleWord class.
      /// </summary>
      /// <param name="word"></param>
      /// <param name="description"></param>
      /// <param name="points"></param>
      public ScrabbleWord(string word, 
      string description, int points)
      {
      this.word = word;
      this.description = description;
      this.points = points;
      }


      public override string ToString()
      {
        return string.Format(
        "Word: {0}, Description: {1}, Points: {2}", 
          word, description, points);
      }
    }
  }
}

Biography

Paul Kimmel is a software architect for TriState Hospital Supply, columnist, book author, Microsoft MVP, and .NET User Group president. You may contact him at pkimmel@softconcepts.com if you have technology questions or are interested in joining or starting a users group.