var_dump：string(0)“”

我正在尝试检查数组的一部分是否不为空,然后显示代码,但代码显示无论如何.

我试过！is_null！空.我不确定哪个应该是正确的,或者我应该去：
if(sizeof($book [‘Booking’] [‘comments’])> 0)

码：

<?PHP if (!empty($book['Booking']['comments'])) {?>
    <table width="100%" border="0">
        <tbody>
            <tr>
                <td style="font-family:'Lucida Grande',sans-serif;font-size:12px;font-weight:normal;color:#666666;">
                    <?=$book['Booking']['comments']?>
                </td>
            </tr>
        </tbody>
    </table>
<? } ?>

阵：

Array
(
[Booking] => Array
    (
        [id] => 109
        [user_id] => 1
        [corporate_account_id] => 0
        [id_ref] => RES000109
        [price] => 178.00
        [arrival] => 2011-10-18 00:00:00
        [departure] => 2011-10-19 00:00:00
        [rate_title] => 
        [adult_guests] => 4
        [child_guests] => 0
        [company] => gravitate
        [titlename] => 
        [firstname] => SEOn
        [surname] => Gleeson
        [address1] => 8 Crow St
        [address2] => 
        [city] => Dublin
        [state] => Co. Dublin
        [postcode] => 2
        [country] => Ireland
        [phone] => 0863269087
        [mobile] => 
        [fax] => 
        [email] => ger@res360.com
        [comments] => 
        [created] => 2011-10-18 13:40:47
        [updated] => 2011-10-18 13:40:47
        [status] => 1
        [cancelled] => 0
        [request_src] => website
        [request_token] => 0
        [token] => ayzrGnx
        [survey_sent] => 0000-00-00 00:00:00
        [survey_returned] => 0000-00-00 00:00:00
        [send_sms] => 0
        [payment_time] => 0000-00-00 00:00:00
        [fullname] =>  SEOn Gleeson
    )