，php自动ping百度的然后.

求助，php自动ping百度的然后....
小弟有一个php的站，本来程序没有rss自动ping百度的功能，但是我想加一个，于是从网上找了段代码如下：

PHP code

weblogUpdates.extendedPing$url$url”;
$res = postUrl(‘http://ping.baidu.com/ping/RPC2′, $baiduXML);
?>

PHP code

function postUrl($url, $postvar)
{
    $ch = curl_init();
    $headers = array(
        "POST ".$url." HTTP/1.0",
        "Content-type: text/xml; charset=\”utf-8\"",
        "Accept: text/xml",
        "Content-length: ".strlen($postvar),
    );
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $postvar);
    $res = curl_exec ($ch);
    curl_close ($ch);
    return $res;
}

$url = ''; //不知道这个值是什么
$baiduXML = "weblogUpdates.extendedPing$url$url";
echo $res = postUrl('http://ping.baidu.com/ping/RPC2', $baiduXML);