今天发现一个很好用二维数组排序的php方法，usort，推荐给大家，以后二维数组里面，要按照一个字段的值排序用这个方法简单高效，例如下面的数组：
[guess_subject] => Array ( [0] => Array ( [subject_id] => 4587 [game_id] => 9228 [parent_category_id] => 78 [subject_title] => 全场比赛两队总得分之和是 [subject_date_time] => 1490668200 [status] => 2 [subject_answer] => 0 [totle_join] => 0 [max_nickname] => [max_currency] => ) [1] => Array ( [subject_id] => 4588 [game_id] => 9228 [parent_category_id] => 78 [subject_title] => 本场比赛是否有加时赛 [subject_date_time] => 1490668200 [status] => 2 [subject_answer] => 0 [totle_join] => 0 [max_nickname] => [max_currency] => ) [2] => Array ( [subject_id] => 4584 [game_id] => 9228 [parent_category_id] => 78 [subject_title] => 第二节两队总得分之和是 [subject_date_time] => 1490668200 [status] => 1 [subject_answer] => 0 [totle_join] => 0 [max_nickname] => [max_currency] => ) [3] => Array ( [subject_id] => 4585 [game_id] => 9228 [parent_category_id] => 78 [subject_title] => 第三节两队总得分之和是 [subject_date_time] => 1490668200 [status] => 2 [subject_answer] => 0 [totle_join] => 0 [max_nickname] => [max_currency] => ) )
要按照status字段的升序排列的话，只需要这样写
foreach($data as $key => &$value) {
// 按照status的升序排序,使用用户自定义的比较函数对数组中的值进行排序,
// 本函数将用用户自定义的比较函数对一个数组中的值进行排序。 如果要排序的数组需要用一种不寻常的标准进行排序，那么应该使用此函数。
// 在第一个参数小于，等于或大于第二个参数时，该比较函数必须相应地返回一个小于，等于或大于 0 的整数。
usort($value['guess_subject'], function($a, $b){
if ($a['status'] == $b['status'])
return 0;
return ($a['status'] < $b['status']) ? -1 : 1;
});
}
return $data;就会按照status的 升序排列啦， status=1 的数组单元会排在前面
