public function sortArr()
{
$user_list = [
['name' => '张三', 'age' => 28],
['name' => '赵六', 'age' => 21],
['name' => '王五', 'age' => 20],
['name' => '李四', 'age' => 21]
];
array_multisort(array_column($user_list, 'age'),SORT_ASC,$user_list);
echo "<pre>";
var_dump($user_list);
$user_list = [
['name' => 'candy', 'age' => 28],
['name' => 'ac', 'age' => 21],
['name' => 'Bd', 'age' => 18],
['name' => 'abby', 'age' => 20],
['name' => 'fly', 'age' => 21],
['name' => 'Ay', 'age' => 26]
];
$user_list_name = array_map("strtolower",array_column($user_list, 'name'));
array_multisort($user_list_name,SORT_ASC,SORT_STRING,$user_list);
var_dump($user_list);
}