Forumhome error

Can someone please tell me what I am getting this error on my forumhome?

Warning: Unknown modifier 'k' in /home/bear/public_html/forum/index.php on line 414

Here is the chunk of code in question:

PHP Code:

// vbarchive robot info for currently active users
  $loggedins=$DB_site->query("SELECT session.useragent FROM session WHERE userid=0 AND lastactivity>$datecut");
  $numberwebrobots=0;
  $loggedinrobots="";

    while ($loggedin=$DB_site->fetch_array($loggedins)) {
      $checkagent = $loggedin['useragent'];
      $webrobot = useragentcheck($checkagent, 1);
        if ($webrobot)
        {
          $numberwebrobots++;
          if (!(preg_match("/$webrobot/i", $loggedinrobots) )) $loggedinrobots .= $webrobot . ", ";
        }
    }
  if (!empty($loggedinrobots)) $loggedinrobots = "(" . substr($loggedinrobots, 0, -2) .")";
  $numberguest = ($numberguest - $numberwebrobots);
// vbarchive robot info for currently active users end 

Line 414 of this is:

PHP Code:

          if (!(preg_match("/$webrobot/i", $loggedinrobots) )) $loggedinrobots .= $webrobot . ", "; 

And here is the web robot in question:

Teoma/Ask Jeeves

[thuffner]

I'd just reupload an original copy of index.php to fix the problem

[WEForums]

He wants to fix the problem though and keep his hacks.

[Boofo]

Yes, I would like to keep the others hacks. I know the problem lies in that piece if code. I'm just not sure how to fix the one line though.

[WEForums]

What does "k" mean?

[Boofo]

I'm in the dark as much as you are on that one.

[filburt1]

Try using preg_quote on the useragent first.

[Boofo]

How do you mean?

[filburt1]

PHP Code:

if (!(preg_match("/" . preg_quote($webrobot) . "/i",
    $loggedinrobots) )) $loggedinrobots .= $webrobot . ", "; 

[Boofo]

Ok, I took out:

if (!(preg_match("/$webrobot/i", $loggedinrobots) )) $loggedinrobots .= $webrobot . ", ";

and put in it's place:

if (!(preg_match("/" . preg_quote($webrobot) . "/i", $loggedinrobots) )) $loggedinrobots .= $webrobot . ", ";

Was the slash in the web robot name the problem then?

And thank you very much for this.