php递归获取一个数组中指定key的值

/**
 * 递归获取一个数组中指定key的值
 * @param $array
 * @param $keys
 * @param string $delimiter
 * @return mixed
 */
function get_deep_value($array, $keys, $delimiter = ".")
{
    $keys = explode($delimiter, $keys);
    $key = array_shift($keys);
    if (sizeof($keys) > 0 && isset($array[$key])) {
        return get_deep_value($array[$key], implode($delimiter, $keys), $delimiter);
    } else {
        return $array[$key] ?? null;
    }
}

$a = [
    "a" => [
        "b" => "error",
        "c" => [
            "d" => [
                "e" => [
                    "f" => "ok",
                ]
            ]
        ]
    ]
];

var_dump(get_deep_value($a, "a.c.d.e.f"));
/**
 * 输出：
 * string(2) "ok"
 */

var_dump(get_deep_value($a, "a.b"));
/**
 * 输出：
 * string(5) "error"
 */

var_dump(get_deep_value($a, "a.b.c"));
/**
 * 输出：
 * NULL
 */