Posted by Paul Lautman on 05/21/06 15:02

Janwillem Borleffs wrote:
> Paul Lautman wrote:
>> I understand a bit more about it now, having tried something else,
>> but I still can't find a difference between usort and uasort and
>> neither can I figure out how to use uksort?
>>
>
> What is going wrong in the code from your previous post is that you
> are using numeric indexes on associative arrays, contained in $x and
> $y, which are using keys instead.
>
> Compare the following implementation with the one from your previous
> post:
> function compare($a, $b) {
> list(,$var_a) = array_values($a);
> list(,$var_b) = array_values($b);
> if ($var_a == $var_b) return 0;
> return $var_a < $var_b ? -1 : 1;
> }
>
> As you will see, list extracts the value from the second index from
> the array returned by array_values when applied to $a and $b.
>
> The difference between usort and uasort, is that the latter preserves
> the index association, while the first doesn't. As an example, with
> usort, the result will always be:
>
> array( 0 => ..., 1 => ....);
>
> while with uasort, depending on the structure of the original array,
> the result can be:
>
> array( 1 => ..., 0 => ....);
>
> The uksort function uses the keys/indexes, while the uasort function
> uses the values for sorting. For the array structure you've posted,
> uksort appears to be useless.
>
>
> JW
Yeah I worked out the indexes problem.

Can you give me an example of where usort and uasort give different outputs
and how uksort would be used?

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