static void Main(string[] args) { BookCollection collection = new BookCollection(); collection[0] = new Book("Harry Potter"); collection[1] = new Book("Lord of the Ring"); collection[2] = new Book("Dac Nhan Tam"); // Create iterator Iterator iterator = collection.CreateIterator(); // Skip every other item iterator.Step = 1; System.Console.WriteLine("Iterating over collection:"); for (Book book = iterator.First(); !iterator.IsDone; book = iterator.Next()) { System.Console.WriteLine(book.Name); } // Wait for user System.Console.ReadKey(); }