How to deny special chars ?

Anon

I am making a userlogin and I don't want people to use funky usernames that use any special characters, for example:

(\/)i$$_Kr@zy

I want all the usernames to be ONLY LETTERS and no spaces, anything else is out.

Let's say I use $username in my code, what code could I use to check $username for special chars, then echo "Change username" if it finds any.

Thanks in advance!

Anon

I forgot about numbers, include numbers too.

Instead of making a string of special characters and searching for them in $username, I think it would be easier to check whether or not each character in $username is a letter a-z or a number 0-9, but how could i go about doing that?

$username will only be about 20 chars long max so it shouldnt be a problem.

cheald

if(!eregi("[^{a-z0-9]",$username))} {
//it has only letters and numbers
}

Anon

if(preg_match("/^{[a-z0-9]+$/i",} $username)

I stay away from the ereg functions because they benchmark significantly slower than the preg equivalent.

http://www.php.net/manual/en/ref.pcre.php
http://www.php.net/manual/en/pcre.pattern.syntax.php

reagent

this may be more readable, i'm not trying to have a pissing contest, just want to show another way 😉

preg_match("/^[\w\d]+$/", $username);

i too prefer preg..

easy
p.

cordex

I stay away from the ereg functions because
they benchmark significantly slower than the
preg equivalent.

Maybe sometimes, but in this instance, no - not on my server. (Sorry, you caught me with my timer testing script up and I had to check this claim out.
For the string:
$username="My UserName is ()()()(";

eregi("[^{a-z0-9]",$username)} clocked in at 1.2222719937563 seconds/100,000

preg_match("/^{[a-z0-9]+$/i",} $username) limped along at 2.6144229918718 seconds/100,000

preg_match("/^[\w\d]+$/", $username) took 2.2509840130806 seconds/100,000

Okay, I'm done. puts timer script away