[mtha]

PHP Code:

if (!$userinfo['invisible'] OR $showinvisible) 
{ 
    if (!empty($currentthread['whoviewed'])) 
    { 
        if (!in_array($bbuserinfo['userid'], $vieweduserids)) 
        { 
            $DB_site->query("UPDATE ".TABLE_PREFIX."thread SET whoviewed = CONCAT(whoviewed, \" \", \"" .$bbuserinfo['userid'] . "\") WHERE threadid = $threadid"); 
        } 
    } 
    else 
    { 
        $DB_site->query("UPDATE ".TABLE_PREFIX."thread SET whoviewed = \"" . $bbuserinfo['userid'] . "\" WHERE threadid = $threadid"); 
    } 
} 


It seems like this code will record "guest id = 0" too.
Should it check if $bbuserinfo['userid'] exist?