Ordering by surname (WordPress)

Ordering by surname (WordPress)

    $my_query = null;
    $my_query = new WP_Query($args);

    $docs = $my_query->posts;

    function lastNameSort($a, $b)
    {
        $aLast = end(explode(' ', $a->post_title));
        $bLast = end(explode(' ', $b->post_title));

        return strcasecmp($aLast, $bLast);
    }

    uasort($docs, 'lastNameSort');

    foreach ($docs as $doc) {
        $output .= '<option value="'.
                get_permalink($doc->ID).
                 '">'.
                $doc->post_title.
                '</option>';
    }

    wp_reset_query();