Well, let's give it a day or two and see what happens. I'm not all that good with regexes.
This will match only the last 2 digits if they are numbers:
/[0-9]{2}$/
So it may look like this:
$username="fish23";
if (preg_match_all('/[0-9]{2}$/i', $username, $result)==1)
{
echo "Match found";
}
else
{
echo "no match found";
}
