On 3/14/2010 9:54 PM, Ashley M. Kirchner wrote:
I'm not a regexp person (wish I was though), and I'm hoping someone can give
me a hand here.  Consider the following strings:

-          domain\usern...@example.org

-          domain\username

-          the same as above but with / instead of \  (hey, it happens)

-          usern...@example.org

-          username

Essentially I have a sign-up form where folks will be typing in their
username.  The problem is, in our organization, when you tell someone to
enter their username, it could end up being any of the above examples
because they're used to a domain log in procedure where in some cases they
type the whole thing, in other cases just the e-mail, or sometimes just the

So what I'd like is a way to capture just the 'username' part, regardless of
what other pieces they put in.  In the past I would write a rather
inefficient split() routine and eventually get what I need.  With split()
getting deprecated, I figured I may as well start looking into how to do it
properly.  There's preg_split(), str_split(), explode() . possibly others.

So, what's the proper way to do this?  How can I capture just the part I
need, regardless of how they typed it in?



The basic problem is that the slashes are legitimate characters for usernames per the RFC 5322; http://en.wikipedia.org/wiki/E-mail_address

However, per the "Notwithstanding the addresses permitted by these standards...." paragraph, I disallow the "! # $ % * / ? ^ ` { | } ~" and have not found a problem.

You didn't mention whether you had control over the whole submission process. If so, I'd suggest checking the submitted address and sending back to the client a message asking them to correct their submission and resending it.

You can check for any of the above characters and bounce the submission back to the client.

Check out filter_var($emailAddr, FILTER_VALIDATE_EMAIL) It will catch a lot of errors.

Also, you'll find the helpful preg_match("%[[:alnum:][:punct:]]%", $addr); These are legit characters. First remove everything following the @ and the @ itself. Obviously, you can use if(!preg_match....) to catch anything not valid.

There are several str functions that'll do it or simply preg_replace("%...@.*%", '', $addr)

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