Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

C# Querying With LINQ Query Operators Generation Operators

Posted by Jessie Cui
Jessie Cui
7,607 Points

DefaultIfEmpty

Does DefaultIfEmpty only return a one value set of the default value? Or does it also mutate the set it was called on, if it was empty, and change it to a set with one instance of it's default value?

1 Answer

Steven Parker
Steven Parker
231,269 Points
Steven Parker
Steven Parker
231,269 Points

DefaultIfEmpty does not mutate the set it was called on.

If the set is empty, it returns a singleton collection (your "one value set") containing the default value for the type.

For more information, see the MSDN Documenation.