使用array_search进行多维数组

function multi_array_search($needle, $haystack) {
    if (is_array($haystack)) {
        foreach ($haystack as $key => $value) {
            if (is_array($value)) {
                $result = multi_array_search($needle, $value);
                if ($result !== false) {
                    return $result;
                }
            } elseif ($value == $needle) {
                return $key;
            }
        }
        return false;
    } else {
        return false;
    }
}

$array = array(
    'fruit' => array('apple', 'banana', 'orange'),
    'vegetable' => array('carrot', 'potato', 'onion')
);

$result = multi_array_search('banana', $array);
if ($result !== false) {
    echo "Found at key: $result";
} else {
    echo "Not found";
}

Found at key: fruit.1