Return an empty IEnumerator

c# ienumerator
David Božjak picture David Božjak · Nov 11, 2009 · Viewed 28.2k times · Source

I have an interface that, among other things, implements a "public IEnumerator GetEnumerator()" method, so I can use the interface in a foreach statement.

I implement this interface in several classes and in one of them, I want to return an empty IEnumerator. Right now I do this the following way:

public IEnumerator GetEnumerator()
{
    ArrayList arr = new ArrayList();
    return arr.GetEnumerator();
}

However I consider this an ugly hack, and I can't help but think that there is a better way of returning an empty IEnumerator. Is there?

Answer

Jon Skeet picture Jon Skeet · Nov 11, 2009

This is simple in C# 2:

public IEnumerator GetEnumerator()
{
    yield break;
}

You need the yield break statement to force the compiler to treat it as an iterator block.

This will be less efficient than a "custom" empty iterator, but it's simpler code...

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