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<Author>`, 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 firstname's equalling Bob from `authorsList`? Note: This is a simplified example for the purposes of the question.

Accepted 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<Author>(authors);
authorsList.RemoveAll(x => setToRemove.Contains(x));
```

Using LINQ to remove elements from a List<T>

Solution

Problem