When IEnumerator.Reset() method is called?

Question

let's have this code :

class MyList : IEnumerable, IEnumerator
{
    int[] A = { 1, 2, 3, 4, 5 };
    int i = -1;

    #region IEnumerator Members

    public object Current
    {
        get { return A[i]; }
    }

    public bool MoveNext()
    {
        i++;
        return i < 5;
    }

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

    #endregion

    #region IEnumerable Members

    public IEnumerator GetEnumerator()
    {
        return (IEnumerator)this;
    }

    #endregion
}

And In Main Method :

MyList list = new MyList();
foreach (int i in list)
{
    Console.WriteLine(i);
}

foreach (int i in list)
{
    Console.WriteLine(i);
}

Why the second foerach doesn't work ?? and the "i" doesn't initialize again ??

Is that true : Reset method should be called automatically before foreach is executed ??

why it doesn't call here ??

Answer 1

Reset is redundant; so much so that it is a requirement in the language spec for iterator blocks to throw an exception on Reset. The correct thing to do is simply dispose and release the old iterator, and call GetEnumerator again. Or better: avoid having to read it twice, since not all data is repeatable.