Reorder a PHP array with usort and strcomp: bug

Question

Using usort and strcomp together to order an array by one of its keys has an odd effect: it returns my array with fewer items in it than I put in.

The array in my case contains rows representing tasks, and I want to order the rows in the array by the key 'displayorder', which is a number but which I want to be sorted in alphabetical manner (don't ask why).

function treeSort($a, $b) {
        return strcmp(strval($a['displayOrder']), strval($b['displayOrder']));
    }

usort($tree, "treeSort");

There are nine rows, but I only get six of them back. Those six are nicely sorted, by the way. If I use uasort instead of usort, I do get all nine rows, but ordered in a numerical way.

Answer 1

I've found a solution: array_multisort. That's probably what you'd have proposed Tim if I had given you the details on $tree.

Got the code from the examples in the documentation on array_multisort:

foreach ($tree as $key => $row) {
        $sortOrder[$key] = $row['displayOrder'];
    }
    array_multisort($sortOrder, SORT_STRING, $tree);