Comments on: Array

by: Jim

Fri, 23 Dec 2005 20:41:07 +0000

I’m new to Objective C (well, just about any C as a practical matter). This is the single most useful blog I’ve come across. Thanks.

by: Michel Fortin

Fri, 23 Dec 2005 22:54:11 +0000

Being pretty familiar with PHP arrays from the PHP side, you intrigued me enough for me to look at PHP’s array code in the Zend engine.

It’s a hash table and a linked list at the same time: each element of the table contains a pointer to next and previous elements, making them a *ordered* linked list. There is nothing polymorphic in there, nor would I think it could give much improvements since PHP arrays are never really accessed by index, always by key. It’s more like an ordered dictionary. :-)

by: indyJT Weblog » In Soviet Russia you don’t second guess Apple, Apple second guesses YOU

Fri, 23 Dec 2005 22:56:33 +0000

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Fri, 23 Dec 2005 23:52:48 +0000

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by: Maarten Sneep

Sat, 24 Dec 2005 02:47:56 +0000

Hi, I think you left out a zero in the numbers when describing the CF results. Makes it a bit more confusing than it needs to be.

Maarten

by: ridiculous_fish

Sat, 24 Dec 2005 03:04:54 +0000

Thanks, Maarten! I’ve fixed that.

by: nicolas

Sat, 24 Dec 2005 06:15:56 +0000

Love your blog !
What about sorting ?
I’d love to see your cunning analysis compare NSArray sorts with objective C sort methods and C arrays with qsort().
(Unless I’m wrong, you’re an apple guy), you should be funded by your group to run a weekly (?) entry here !

by: Aaron Jensen

Sat, 24 Dec 2005 10:01:04 +0000

Does this really matter? I mean, in the five years I’ve been developing, I’ve never used arrays that have more than 1,000 elements. Yes, I believe there is some software that actually has 100,000+ element data structures, but I think they are few and far between. Are they?

by: Zac Bedell

Sat, 24 Dec 2005 15:51:28 +0000

I’ve been working on an app that deals with 100,000+ element arrays lately, so this was a very interesting read. Thank you!

To respond to nicolas’ comment: NSArray’s sorting methods appear comparable to qsort at least for between 20,000 and 40,000 objects. I found that for my purposes (sorting arrays that are usually *mostly* sorted), implementing a category on NSMutableArray which used the standard C library’s mergesort was significantly faster. Given what I’ve learned of NSArray today, I think I have some more benchmarking to do.

My link on this post is to what benchmarks I’ve done.

by: Jens Alfke

Sat, 24 Dec 2005 18:00:26 +0000

If you want to read some interesting array-implementation stuff, take a look at the excellent paper on the implementation of Lua 5.0:
http://www.tecgraf.puc-rio.br/~lhf/ftp/doc/jucs05.pdf
Lua’s arrays are basically like PHPs (array plus dictionary) but they’ve put in some very interesting space and speed optimizations; which is important, because Lua uses arrays for everything. (I recommend Lua in general; it’s a very compact, elegant language.)