php 二维数组排序

function multi_compare($a, $b)
{
    $val_arr = array(
            'gold'=>'asc',
            'silver'=>'desc'//还可以增加额外的排序条件
    );
    foreach($val_arr as $key => $val){
        if($a[$key] == $b[$key]){
            continue;
        }
        return (($val == 'desc')?-1:1) * (($a[$key] < $b[$key]) ? -1 : 1);
    }
    return 0;
}

$arr = array(
    array('gold'=>1, 'silver'=>2),
    array('gold'=>8, 'silver'=>10),
    array('gold'=>8, 'silver'=>8),
    array('gold'=>2, 'silver'=>1),
);

uasort($arr, 'multi_compare');

ee($arr);