使用curlpost数据有关问题

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true);
// 数据为string类型时，超时；
// 如果是array('param' => $data_string)就没问题。
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_TIMEOUT, 3);
curl_exec($ch);
curl_close($ch);

$data_string = "ispost=ok&msg=post";
$data = array("ispost"=>"ok","msg"=>"post");
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://localhost/my/www/getdata.php");
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_TIMEOUT, 30);
$result = curl_exec($ch);
curl_close($ch);
echo $result;