Initialize an integer array with a single value in C# .NET

Question

Possible Duplicate:
How do I quicky fill an array with a specific value?

Is there a way to initialize an integer array with a single value like -1 without having to explicitly assign each item?

Basically, if I have

int[] MyIntArray = new int[SomeCount];

All items are assigned 0 by default. Is there a way to change that value to -1 without using a loop? or assigning explicitly each item using {}?

Also check out this http://stackoverflow.com/questions/13980570/how-to-intialize-integer-array-in-c-sharp/ which discusses how to do it efficiently and http://stackoverflow.com/questions/10519275/high-memory-consumption-with-enumerable-range how not to use ToArray for large arrays. — Alexei Levenkov, Jan 08 '13 at 07:55

score 45 · Accepted Answer · edited Jan 08 '13 at 07:54

45

int[] myIntArray = Enumerable.Repeat(-1, 20).ToArray();

edited Jan 08 '13 at 07:54

Eren Ersönmez

answered Jan 08 '13 at 07:48

scartag

3

Don't forget the `.ToArray()` – mlorbetske Jan 08 '13 at 07:51
4

+1 for all ToArray once. Before using please read [High memory consumption with Enumerable.Range](http://stackoverflow.com/questions/10519275/high-memory-consumption-with-enumerable-range) if your array is large. – Alexei Levenkov Jan 08 '13 at 07:57
And for types other than int, use the template form, eg. Enumerable.Repeat(1,20).ToArray(); – dlchambers Sep 06 '16 at 19:20
@dlchambers or `Enumerable.Repeat(1U, 20).ToArray();` – tuespetre Oct 26 '17 at 20:44

score 18 · Answer 2 · answered Jan 08 '13 at 07:48

18

You could use the Enumerable.Repeat method

int[] myIntArray = Enumerable.Repeat(1234, 1000).ToArray()

will create an array of 1000 elements, that all have the value of 1234.

answered Jan 08 '13 at 07:48

SWeko

score 14 · Answer 3 · edited Jan 08 '13 at 07:55

14

If you've got a single value (or just a few) you can set them explicitly using a collection initializer

int[] MyIntArray = new int[] { -1 };

If you've got lots, you can use Enumerable.Repeat like this

int[] MyIntArray = Enumerable.Repeat(-1, YourArraySize).ToArray();

edited Jan 08 '13 at 07:55

Habib

answered Jan 08 '13 at 07:45

mlorbetske

1

put some size in new int[Size] and this statement will not work. Even if you put a static size like 50. So, I don't think that this is right answer. – Farhan Hafeez Jan 08 '13 at 07:48
1

@FarhanHafeez You're absolutely correct, I originally misread the question and immediately went to edit my answer, my apologies – mlorbetske Jan 08 '13 at 07:49
Only answer to address the "without using a loop" – Paul Childs Jan 20 '22 at 06:46

3 Answers3