Using LINQ to remove elements from a List

Question

Say that I have LINQ query such as:

var authors = from x in authorsList
              where x.firstname == "Bob"
              select x;

Given that authorsList is of type List, how can I delete the Author elements from authorsList that are returned by the query into authors? Or, put another way, how can I delete all of the Bob's from authorsList? Note: This is a simplified example for the purposes of the question.

Answer

Well, it would be easier to exclude them in the first place:

authorsList = authorsList.Where(x => x.FirstName != "Bob").ToList();

However, that would just change the value of authorsList instead of removing the authors from the previous collection. Alternatively, you can use RemoveAll:

authorsList.RemoveAll(x => x.FirstName == "Bob");

If you really need to do it based on another collection, I'd use a HashSet, RemoveAll and Contains:

var setToRemove = new HashSet(authors);
authorsList.RemoveAll(x => setToRemove.Contains(x));

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