对于递归键，搜索后可能需要这样的东西：

function get_all_after_array_key($array,$key){
    $currentKey = array_search($key, array_keys($array));
    $hasNextKey = (isset($array[$currentKey + 1])) ? TRUE : FALSE;
    $array = array_keys($array);
    $after = [];
    do {
        if(isset($array[$currentKey + 1])) {
            $hasNextKey = TRUE;
            $after[] = $array[$currentKey + 1];
            $currentKey = $currentKey + 1;
        } else {
            $hasNextKey = FALSE;
        }
    } while($hasNextKey == TRUE);
    return $after;
}

使用array_search函数的解决方案：

$array = [441, 212, 314, 406];
$val = 441;

$currentKey = array_search($val, $array);

//Check for possible bool value returned by array_search
//Check for possible random index values

if(!is_bool($currentKey) & array_is_list($array)) {
  $before = $array[$currentKey ? $currentKey-1 : count($array)-1];
  $after = $array[($currentKey != count($array)-1) ? $currentKey+1 : key($array)];
}

var_dump($before, $after);

输出：

int(406)
int(212)

http://php.net/manual/en/function.array-search.php

$key = array_search ('441', $arr);
$beforeKey = $key-1;
if($beforeKey<1)
{ $beforeKey = count($array)-1; }
$afterKey = $key+1;
$beforeValue = $array[$beforeKey];
$afterValue = $array[$afterKey];