[SOLVED] A complex Regular Expression for usernames

[Goldeneye]

Hello,

 

I'm tweaking my PHP user-registration script for a site/forum of mine and I've been trying to write a Regex that'll allow the following parameters to be used as a username:

White-Spaces (non-consecutive)

Alpha-Numeric

And miscellaneous characters (_ - .)

With a minimum character limit of 4 and a maximum character limit of 16.

 

So matches would include:

Foobar
Foo bar
Foo_bar
F-o o_b.ar
1F-o2 o_b.3ar4

 

And non-matches would include:

Foo    bar
$Foobar
Foo    %#@

 

I've searched a few sites and tried putting one together, but success wasn't going to come. So how would one go about creating a Regular Expression (or two) that'll match these parameters?

[Third_Degree]

Edit: Oh sorry, didn't read your post thoroughly enough, hold on I'll get code back to you in a second.

[corbin]

if(preg_match('/^[\w_\. -]{4,16}$/', $username) && !preg_match('/[ ]{2,}/', $username)) {

 

}

 

Should work, but someone else might be able to get it into 1 regexp....

[Goldeneye]

Well two Regular Expressions is good for me. I was trying to get it into a single one, but it just wouldn't co-operate with me. Anyways, thanks a lot! I'll have to wait to test this, though, as my website seems to be giving a 503 error at the moment.

[Goldeneye]

Hmmm it doesn't appear to be working.. Here's how I'm using it..

<?php
if(!preg_match('/^[\w_\. -]{4,16}$/', $_POST['pseudonym']) && preg_match('/[ ]{2,}/', $_POST['pseudonym'])) {
	echo '<p class="errmessage">Usernames are to be between 4 and 16 characters with numbers, non-consecutive-whitespaces, letters, and a few miscellaneous characters.</p>';
}
?>

[corbin]

It should be

 

if(preg_match('/^[\w_\. -]{4,16}$/', $_POST['pseudonym']) && !preg_match('/[ ]{2,}/', $_POST['pseudonym'])) {

 

 

If we go through the two patterns, this is the first one:

Starting from the beginning (^ thing),

\w (meaning word characters.... alphanumeric basically) _ .  "" or - repeated 4 to 16 times

String ends

 

Second pattern:

Space repeated twice anywhere in the string.

 

So, you would want the first to match, and the second to not match.

 

 

(If you want to avoid regexp on the second you could do

 

if(preg_match('/^[\w_\. -]{4,16}$/', $_POST['pseudonym']) && strpos($_POST['pseudonym'], "  ") === false) {

 

)

[Goldeneye]

Nevermind, I got it figured out. I wanted it to return a message if the user-input didn't match the Regex. So I just changed:

 

<?php
if(!preg_match('/^[\w_\. -]{4,16}$/', $_POST['pseudonym']) && preg_match('/[ ]{2,}/', $_POST['pseudonym'])) {
	echo '<p class="errmessage">Usernames are to be between 4 and 16 characters with numbers, non-consecutive-whitespaces, letters, and a few miscellaneous characters.</p>';
}
?>

 

To...

 

<?php
if(!preg_match('/^[\w_\. -]{4,16}$/', $_POST['pseudonym']) || preg_match('/[ ]{2,}/', $_POST['pseudonym'])) {
	echo '<p class="errmessage">Usernames are to be between 4 and 16 characters with numbers, non-consecutive-whitespaces, letters, and a few miscellaneous characters.</p>';
}
?>

 

I made it so it says "If no PREG_MATCH() for first Regex OR is PREG_MATCH() for second Regex, echo..." That way, it doesn't require that both parameters are met to be able to display the error message.