How do I display the values of an array and wrap in tags?

In the controller I define the following:

$codes = $this->objUser->GetGroupCodeArray();

In the corresponding template (btw, I may want to move this functionality on the header which is included in every page, how do I get it to do that?), I have the following:

foreach($codes as $code)
  echo '<a href="whatever.php">'.$code.'</a>';

My desired result is that this array which has a bunch of code with a many-to-many association to the user (a user can have many codes, and each code can have many users), is output with the a-tag wrapped around each one individually with a dynamic href.

But I get an error:

Fatal error: Method GroupCode::__toString() must not throw an exception

Help?

also in a a debugging way you could use var_dump($cod);

or

echo "<pre>";
print_r($code);
echo "</pre>";

hth