Which is better, Enumerable.Empty<T> or new[0]?

Question

These are the same:

IEnumerable<string> i;
i = Enumerable.Empty<string>();
i = new string[0];

So, which to use?

I think the first communicates intent more clearly, but it is bigger and a bit noisier, not to mention ugly in the debugger. The second is also more efficient in memory and CPU, if I'm reading Reflector right.

I'm leaning towards the new type[0], but wanted to know what you all think.

Answer 1

Enumerable.Empty<T> caches the creation of the empty array, so the same array will be always be returned, while the second statement creates a new array with each call.

I would tend to Enumerable.Empty<T>, as it shows the intention of the programmer more clearly, and also because using an explicit array creation because of memory usage is premature optimization in a managed program, as the runtime will almost always allocate more than necessary memory to the process anyway.

Answer 2

The difference in terms of performance/memory usage is incredibly negligible in this situation, so that would not be my deciding factor.

I would personally use Enumerable.Empty, mainly because it very clearly describes the developer intent.

Answer 3

It looks to me like Enumerable.Empty delegates to EmptyEnumerable which returns an array of length 0. But it returns the same one every time, and keeps that empty array alive forever.