note 109493 added to function.usort

Jian Wu, actually your code doesn't preserve the original order. It works for arrays with few entries, but if you try it for, say, array of 9 objects, you can see that the order is random no matter 0 or 1 you return when values are equal. I needed a way to make usort() key-preserving, and came up with the most straight-forward way: when the values are equal, we additionally compare the keys. Unfortunately, usort()'s $callback function doesn't have parameters for keys, and array_search() is slow, so I used uksort() for that. (my goal was to sort a list of strings by number of '/'es in them) <?php $urls = [ 'url://somehost/', 'url://somehost/1.htm', 'url://somehost/2_dir/', 'url://somehost/3.htm', 'url://somehost/dir_4/', 'url://somehost/dir_4/subdir/', 'url://somehost/2_dir/file.txt', ]; uksort($urls, function ($a, $b) use ($urls) { $countA = substr_count($urls[$a], '/'); $countB = substr_count($urls[$b], '/'); if ($countA != $countB) { return $countA - $countB; } else { return $a - $b; } }); print_r($urls); ?> output: Array ( [0] => url://somehost/ [1] => url://somehost/1.htm [3] => url://somehost/3.htm [2] => url://somehost/2_dir/ [4] => url://somehost/dir_4/ [6] => url://somehost/2_dir/file.txt [5] => url://somehost/dir_4/subdir/ ) (as you can spot, uksort() preserves the keys, so if you want straight 0..N keys, you can use array_values()) ---- Server IP: 195.221.21.36 Probable Submitter: 188.40.47.196 (proxied: 212.198.166.77) ---- Manual Page -- http://www.php.net/manual/en/function.usort.php Edit -- https://master.php.net/note/edit/109493 Del: integrated -- https://master.php.net/note/delete/109493/integrated Del: useless -- https://master.php.net/note/delete/109493/useless Del: bad code -- https://master.php.net/note/delete/109493/bad+code Del: spam -- https://master.php.net/note/delete/109493/spam Del: non-english -- https://master.php.net/note/delete/109493/non-english Del: in docs -- https://master.php.net/note/delete/109493/in+docs Del: other reasons-- https://master.php.net/note/delete/109493 Reject -- https://master.php.net/note/reject/109493 Search -- https://master.php.net/manage/user-notes.php