I recently upgraded to Ubuntu 10.04 which includes php 5.3.2. Not long after upgrading, I noticed that transactions in my stock tracking program were no longer sorting correctly. At first, I thought the sort function, uksort, might have subtly changed. But, no, the manual didn't mention anything, and the manual and comment examples appeared to line-up with my code nicely.
Next, I checked the apache error log where I got my first clue as to the madness I was about to uncover:
PHP Warning: uksort(): Array was modified by the user comparison function in ... on line 195I double-checked my code. Nope. No modification of the array being sorted. What gives? I was using a global statement so that I could access the array being sorted...
A Google search on the global statement turned up another way to access global variables, the $GLOBALS array. Could php be overzealously assuming that access of a variable via a global statement constitutes modification? Well, maybe using $GLOBALS would solve that problem.
I switched from global to $GLOBALS, and, voila, sorting worked again! Apparently php does equate using a global variable via the global statement to modification of that variable. Geez!
P.S. uksort was returning a false value indicating that the sort had failed.
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Thanks a lot!
ReplyDeleteSpent time on this...
It seems to me pretty obvious that the uksort() function may need global to access the array - since uksort only provides the keys!
Why did they perform that *silent* change :--((
It even seems that $GLOBALS isn't enough:
ReplyDeletefunction cmpdates($a, $b) {
$arr = &$GLOBALS["arr"];
}
stil results in the warning...
of course this is possible:
function cmpdates($a, $b) {
$arr = $GLOBALS["arr"];
}
but this copies the whole array each time cmpdates is called!
Wow. I didn't realize php would be doing something so ridiculous. Thanks for the comment, Dinne. Let us know if you find a better way!
ReplyDelete