Creating a List of given size, all initialized to some value, in C#

Question

Is there a compact manner in which the following can be done?

List<int> a = new List<int>();

for (int i = 0; i < n; ++i)
   a.Add(0);

i.e., creating a list of n elements, all of value 0.

That's pretty compact. And maybe yes, there's a "smooth" or fancy way to do it, but what you've written is clear to even novice developers. Good enough! — James Cronen, Oct 08 '13 at 01:57
So, maybe a duplicate of this: http://stackoverflow.com/questions/2032411/is-there-a-way-to-fill-a-collection-using-a-linq-expression — James Cronen, Oct 08 '13 at 01:57
possible duplicate of [Auto-initializing C# lists](http://stackoverflow.com/questions/1104457/auto-initializing-c-sharp-lists) — CodeNaked, Oct 08 '13 at 02:09
possible duplicate of [Fill List with default values?](http://stackoverflow.com/questions/3363940/fill-listint-with-default-values) — Qantas 94 Heavy, Apr 14 '14 at 09:14

score 17 · Accepted Answer · answered Oct 08 '13 at 02:03

17

Enumberable.Repeat would be the shortest method I can think of:

var a = Enumerable.Repeat(0, n).ToList();

answered Oct 08 '13 at 02:03

Khan

1

It's worth calling out that the `Enumerable` methods have the benefit of being lazy if you don't invoke the `ToList` up front. – Preston Guillot Oct 08 '13 at 02:04

score 7 · Answer 2 · answered Oct 08 '13 at 02:04

7

You can use the Enumerable.Repeat generator:

var list = new List<int>(Enumerable.Repeat(0, n));

answered Oct 08 '13 at 02:04

porges

score 2 · Answer 3 · edited Apr 14 '14 at 09:22

2

List<int> x = Enumerable.Repeat(value, count).ToList();

edited Apr 14 '14 at 09:22

Qantas 94 Heavy

answered Oct 08 '13 at 02:07

John DeLeon

3 Answers3