thinkphp怎么将多维数组变成一维数组？

Question

Array
(

[0] => Array
    (
        [user_id] => 1
    )

[1] => Array
    (
        [user_id] => 22
    )

)
我只想要 1和22 怎么变成$a=array('1','22');

Answer 1

php版本要大于5.5.0
$userid_array = array_column($x,'userid');


php版本要大于5.4.0
$userid_array = array_map(function($item){return $item['userid'];},$x);

再低就for循环吧