How to get current user thier ID?

[M4GN3T]

Hi Guys,

First time developing a plugin for vBulletin, and i think im about to pass out xD. I'm trying to do the following:

$userid = $vbulletin->userinfo[userid];
$sql="SELECT `xp` FROM  `rank` WHERE  `userid` = '".$userid."'";

To succesfully run this query, i need the current, logged in, user thier user ID. The docs tell me to use userinfo[userid] but its not working for me. Am i doing something wrong? If so, what is it?