reg expression question

[atomicmunky]

i'm trying to get rid of all non-alphanumeric characters from a form input.
i'm using this piece of code:

if ($uname != ""){
if(!eregi("^([[:alnum:]_-])$",$uname)) {
$unameError3 = "<LI>Username can only contain alphanumeric characters</LI>\n";
$send = "no";
}
}

it works. but it works a little too well.
it doesn't matter what is submitted, it always resluts in the error.

anyone have any idea of how to go about it?

[qslack]

Try this:

if ($uname != ""){
if(!eregi("^([a-zA-Z_\-])$",$uname)) {
$unameError3 = "<LI>Username can only contain alphanumeric characters</LI>\n";
$send = "no";
}
}

It may be a problem with the last hypen (PHP might be interpreting it as "all characters between _ and ], inclusive). Or it might be a problem with [:alnum:].

[atomicmunky]

about 5 minutes after i posted the question, i came up with this:

if ($uname != ""){
if (eregi("([^a-zA-Z0-9])+",$uname)){
	$unameError3 =  "<LI>User Name can only contain alphanumeric characters</LI>\n";
        $send = "no";
}
}

and it worked.

that's not to say i didn't appreciate your contribution.
you seem like you know what you're doing, whereas i got lucky with the code.

i did try your version, and i'm glad to say that it worked also.

do you think that i could use it to check more than one form field without coding it several times. along the lines of defining what fields to check and have them checked all in one piece of code?

i think i would come in handy if you wanted to check a whole form (or most of the form) without having to write it out a bunch of times.

thanks again for your help..

[qslack]

I think this would work to return 1 if it is a valid username and 0 if it isn't.

function is_valid_username($uname) {
return eregi("([^a-zA-Z0-9])+",$uname;
}

Then,
is_valid_username("lala#$#$") == 0
is_valid_username("qslack") == 1

[jrap]

Just a quick correction on qslack's code.

<?
function is_valid_username($uname)
{
         return eregi("^[a-z0-9]+$",$uname);
}
?>

is_valid_username("RoB101") returns 1;
is_valid_username("R*o*b#") returns null
is_valid_username("") returns null

Now I am sure Freddy will come along and correct my code ;)?