Sort Object in PHP [duplicate]

Almost verbatim from the manual:

function compare_weights($a, $b) { 
    if($a->weight == $b->weight) {
        return 0;
    } 
    return ($a->weight < $b->weight) ? -1 : 1;
} 

usort($unsortedObjectArray, 'compare_weights');

If you want objects to be able to sort themselves, see example 3 here: http://php.net/usort