Reading an array from an array

Question

I'd like to pull a section of an array out for manipulation.

e.g. From an array that contains 50 items, i want to return items 12 to 22 in a new array

Im currently using LINQ which I am assuming is slow:

return fullArray.Skip(12).Take(22).ToArray();

Is there a quicker way?

@Vijay He's assuming it, but I've tested it (for exactly this Take/Skip scenario) and it is orders of magnitude slower. I agree that he should have profiled first though :) — RB.
– RB., Commented Sep 13, 2013 at 10:47
That's what I was kinda getting at, I know he said "assumed", but people do that all the time with linq and a lot of the time there is little to no difference in performance, at least nothing easily measurable! I'll use this method instead of take/skip for my paging in the future :) — Faraday
– Faraday, Commented Sep 13, 2013 at 11:37

RB. · Accepted Answer · 2013-09-13 10:42:18Z

6

The Array.Copy method is massively quicker than Linq (I've tested it before and it was 2 or 3 orders of magnitude quicker!)

var sourceArray = object[50];
var newArray = object[10];
// Copy 10 elements, starting at index 12, to newArray (starting at index 0)
Array.Copy(sourceArray, 12, newArray, 0, 10);

answered Sep 13, 2013 at 10:42

RB.

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Jimbo Over a year ago

Sorry, Im a bit of a n00b with arrays - thanks for the quick answer!

Soner Gönül · Accepted Answer · 2013-09-13 10:49:42Z

0

You can use Array.Copy Method (Array, Int32, Array, Int32, Int32) method;

Copies a range of elements from an Array starting at the specified source index and pastes them to another Array starting at the specified destination index. The length and the indexes are specified as 32-bit integers.

For example;

int[] array1 = new int[50];
int[] array2 = new int[10];
Array.Copy(array1, 12, array2, array2.GetLowerBound(0), 10);

edited Sep 13, 2013 at 10:49

answered Sep 13, 2013 at 10:43

Soner Gönül

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flindeberg Over a year ago

The reign of the downvoters is here it seems :) Not the first time an answer has been downvoted without reason.

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