Build your own IEnumerator/IEnumerable and use it in foreach loop : IEnumerator « Data Structure « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Data Structure
3. IEnumerator

using System;
using System.Collections;

class LetterEnumerator : IEnumerator
{
   string[] letters;
   int Position = -1;

   public LetterEnumerator(string[] theletters) 
   {
      letters = new string[theletters.Length];
      for (int i = 0; i < theletters.Length; i++)
         letters[i] = theletters[i];
   }

   public object Current                    
   {
      get { return letters[Position]; }
   }

   public bool MoveNext()                   
   {
      if (Position < letters.Length - 1){ 
         Position++; return true; 
      }
      else
         return false;
   }

   public void Reset()                      
   {
      Position = -1;
   }
}

class LetterList : IEnumerable
{
   string[] letters = { "A", "B", "C" };
   public IEnumerator GetEnumerator()
   {
      return new LetterEnumerator(letters);
   }
}

class MainClass
{
   static void Main()
   {
      LetterList mc = new LetterList();

      foreach (string l in mc)
         Console.WriteLine("{0} ", l);

   }
}

A
B
C