#47370 [Asn]: array_unique has backward compatibility problem, and SORT_REGULAR is confusing

ID: 47370 Updated by: jani@php.net Reported By: for-bugs at hnw dot jp Status: Assigned Bug Type: Documentation problem Operating System: * PHP Version: 5.2.9 Assigned To: andrei New Comment: See also bug #48115 (yes, WTF?!) Previous Comments: ------------------------------------------------------------------------ [2009-03-01 07:03:12] moriyoshi@php.net Andrei, you must add a note about the behavioral change. ------------------------------------------------------------------------ [2009-03-01 00:51:32] for-bugs at hnw dot jp Hi, Andrei. Here's another terrible example. <?php $a=array("10","1az", "1e1"); var_dump(array_unique($a)); $b=array("1e1","10", "1az"); var_dump(array_unique($b)); The result is: array(3) { [0]=> string(2) "10" [1]=> string(3) "1az" [2]=> string(3) "1e1" } array(2) { [0]=> string(3) "1e1" [2]=> string(3) "1az" } The array $a and $b have same 3 elements with different ordering. Although, two array_unique() returns different result. First array_unique() returns 3 elements in spite of the fact that "10" equals "1e1" with ==. In fact, the two arrays are both sorted about SORT_REGULAR. Because "10" < "1az" , "1az" < "1e1" and "1e1"=="10". Sorting with SORT_REGULAR is not stable, and unique element is not always in neighbor. This behavior is not obvious for almost all PHP programmer. You should explain the detail of your function in reference manual. ------------------------------------------------------------------------ [2009-02-14 08:28:18] for-bugs at hnw dot jp OK, you think comparing elements as string is harmful, doesn't you? Then, how about array_diff() or array_intersect()? They compare array elements with string representation. Isn't it harmful? ------------------------------------------------------------------------ [2009-02-14 08:22:26] moriyoshi@php.net This was not discussed, and thus no bogus thing. ------------------------------------------------------------------------ [2009-02-13 22:27:35] andrei@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php The slight BC breakage is negligible compared to the benefits of getting it to work properly. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/47370 -- Edit this bug report at http://bugs.php.net/?id=47370&edit=1