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

[filburt1]

It's because $webrobot had characters in it that were being interpreted as part of the regexp.

[Boofo]

Thank you for the fix. That has been bugging me for a while.

[filburt1]

While you're at it, check out http://www.php.net/preg_quote and (IIRC) http://www.php.net/preg . Very useful stuff, that documentation

[Boofo]

Thank you. Now it makes a little more sense. It was the forward slash causing problems. One last question...what is the i for ("/i", ) in the line of code? I mean, what does it do exactly?

[filburt1]

I have no idea. I know that some permutation of "siU" makes the regular expression not "greedy" but beyond that, no idea.

[Erwin]

This is deep stuff. Good work filburt.