serialize数组,如何写到cookie里面就多了个值呢

serialize数组,怎么写到cookie里面就多了个值呢
$a= array();
$a[]= $id;
var_dump($a);
$content = serialize($a);
var_dump($content);
cookie('uid',$content);

------解决思路----------------------

$a = array(1);
$content = serialize($a);
setcookie('uid',$content);

print_r($_COOKIE);

Array
(
    [uid] => a:1:{i:0;i:1;}
)