Convert List<T> to object[]

Question

I am looking for a one liner that transforms List<T> into object[]. It's one liner, so I am not interesting in solutions such as foreach, or for...

Any takers?

Hint: No, both List<T>.ToArray() and List<T>.ToArray<object>() don't work.

Edit: Why List<T>.ToArray<object>() doesn't work? Because it can't compile.

Answer 1

mylist.Cast<object>().ToArray()

That will only iterate once, by the way, in case you were wondering about the performance. O(n). :)

Why? Well, because Cast<object> will use deferred execution and won't actually do anything until the list is iterated by ToArray().

Edit: Alternatively, you could use LINQ to do the same thing in one line with one iteration:

var myObjectArray = (from item in myList select item as object).ToArray();

The first is probably easier to understand and type, but the second is much more fun, because, hey, it's LINQ!

Answer 2

theList.Cast<object>().ToArray()

or

new List<object>(theList).ToArray()

Answer 3

If you don't mind writing a very short, reusable function, the ConvertAll Extension Method might help:

http://msdn.microsoft.com/en-us/library/73fe8cwf.aspx

EDIT:

This would work too

List<int> intList = new List<int>() { 1, 3, 4 };
object[] objectList = intList.ConvertAll(item => (object)item).ToArray();

Answer 4

List<T>.Select(x => x as object).ToArray();

Should return an object[].

Answer 5

And for a pre-LINQ solution (that only works for reference types).

(object[])List<T>.ToArray();

Answer 6

In C# on .NET 2.0 (VS 2008) the following compiles and doesn't use LINQ (as far as I can see) for reference types.

 object[] oArray;
 List<MyObject> oList = new List<MyObject>();
 oArray = oList.ToArray();

This does not require a cast as all reference types have object as their base.

Answer 7

If you don't have Linq (.Net 3.0) then you can use the ConvertAll() and ToArray() methods in List:

List<T> list = new List<T>();

object[] objects = list.ConvertAll<object>(item => (object)item).ToArray();