需要在执行curl_exec后再通过curl_getinfo来获取。

$ch = curl_init ();
curl_setopt($ch, CURLOPT_URL, 'http://www.google.com.hk');
curl_setopt($ch, CURLOPT_TIMEOUT, 200);
curl_setopt($ch, CURLOPT_HEADER, FALSE);
curl_setopt($ch, CURLOPT_NOBODY, FALSE);

curl_setopt( $ch, CURLOPT_POSTFIELDS, "username=".$username."&password=".$password );

curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, FALSE);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');
curl_exec($ch);
$httpCode = curl_getinfo($ch,CURLINFO_HTTP_CODE);