Understanding .Single()

Question

[This is a really tough one to Google.]

Browsing sample code i'm seeing a usage i don't understand:

var orderRow = order.Rows.Single();

Rows is an enumerable and usually one would iterate using a foreach loop. Is the .Single a workaround for cases where, for whatever reason, the foreach can't be (or need not) be used?

thx

In the time since the OP i've learned a bit more about usage that'll help other hits to this question:

var option = options.OfType<AdditionalLocationsOption>().SingleOrDefault();
if (option != null){
...stuff
}

Answer 1

LINQ's Single method returns the single element in a collection.

This would be written in Rows is known to contain exactly one row.
If it's empty, or if it has more than one row, an exception will be thrown.

If you know that the collection has exactly one element, this code is simpler than a foreach loop and makes its intentions clearer.