public class DaysOfTheWeek : System.Collections.IEnumerable
{
    string[] days = { "Sun", "Mon", "Tue", "Wed", "Thr", "Fri", "Sat" };
    public System.Collections.IEnumerator GetEnumerator()
    {
        for (int i = 0; i < days.Length; i++)
        {
            yield return days[i];
        }
    }
}
class TestDaysOfTheWeek
{
    static void Main()
    {
        // Create an instance of the collection class
        DaysOfTheWeek week = new DaysOfTheWeek();
        // Iterate with foreach
        foreach (string day in week)
        {
            System.Console.Write(day + " ");
        }
    }
}