restricting a number of characters

[Randomizer]

I was trying to figure out how to restrict a number of characters in a form i had this:

<?php
$username = "whatever";
$slusername = strlen($username);

if ("3>$slusername>25")
{
// invalid username message or something like that
exit(); //kill script
}

else
{
//register
}
?>

i thought that it would make it so it would restrict you if your username was less than 3 characters or larger than 25, but it always returns with the invalid username message no matter what i input for $username.

many thanx for help

[LordShryku]

You need to use [man]strlen[/man]

[Randomizer]

Sorry i was assuming you would assume i already did that, lol, cause i did

EDIT: I changed it for the sake of your complaining

[LordShryku]

You don't show it, so I assume nothing.
Should I assume you already know the answer to this question?

$this = strlen($username);
if($this < 3 || $this > 25) {
   // invalid
}