On Dec 17, 2008, at 12:04, Stanislas Krásnaya wrote:
I've read that, since we're programming in Objective-C, it's more
elegant and reliable to use an NSArray stuffed with NSNumber instead
of a classic C array. But what I want to do, it's performing classic
calculation, like mean value, variance... etc, on floating point
numbers. Typically around 1000 of them.
I know that our computers are fast now, but this doesn't mean that
we have to not take care of optimization.
So, since NSArray is designed to store all kinds of NSObject's, and
mine will just store some NSNumber's, wouldn't it be a bit stupid to
use it?
There's nothing inelegant about using a classic C array for this. You
can allocate the memory for the array with malloc, for a classic-
classic solution, or allocate the memory as a NSData object for a
classic-hybrid solution. If you only want to do calculations with the
numbers, this seems like the obvious approach.
There's also nothing wrong with using a NSArray of NSNumber objects.
You might consider this solution if you think there might be side
benefits, or if it is easier to code somehow. For example, if you have
a NSArray of NSNumber objects, it's very easy to add a NSTableView to
your interface that displays them.
It's unlikely that calculating mean, variance, etc on 1000 NSNumber
objects is going to be a performance issue, unless you're doing these
calculations over and over.
So, choose the approach that gives the clearest, most maintainable
code, then (if necessary) measure the performance to see whether you
need to optimize your approach.
FWIW.
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