Email validation - What is wrong with my regex code?

Question

I'm trying to validate an email address using preg_match..

But i'm getting this error..

Warning: preg_match(): Unknown modifier '+'

This is my code

preg_match("[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?", $email, $matches);

Can someone tell me what is wrong with my regex?

Thanks

I'd strongly recommend not writing this code yourself. code.google.com/p/php-email-address-validation/source/browse/… — Danack
– Danack, Commented May 11, 2013 at 14:26
even space is a valid char in email..point is don't use regex to parse email..put it as simple as this .*@.* that's it — Anirudha
– Anirudha, Commented May 11, 2013 at 14:26
You can be more restrictive on the right side of the @, which has to be a valid domain name, but yeah, pretty much anything goes on the left. — Mark Reed
– Mark Reed, Commented May 11, 2013 at 14:37

Explosion Pills · Accepted Answer · 2013-05-11 14:24:31Z

2

You need to put delimiters around the regex when you use preg_match. The standard is /. If you use the delimiter in the expression, you have to escape it.

preg_match("/[a-z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+\/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/", $email, $matches);

You could also consider using

filter_var($email, FILTER_VALIDATE_EMAIL);

answered May 11, 2013 at 14:24

Explosion Pills

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3 Comments

Boris the Spider Over a year ago

Also, these expressions (?:[a-z0-9-]*[a-z0-9])? are a little odd. Presumably they could be replaced with [a-z0-9-]*? for simplicity.

HamZa Over a year ago

@BoristheSpider I would think that it should be [a-z0-9-]+? :)

Boris the Spider Over a year ago

@HamZaDzCyberDeV I don't think so, as + requires at least one wheres the construction in a non capturing group followed by a ? which means that it is optional (required zero or one time) - so the expression is saying [a-z0-9-] zero or more times (i.e. a *). On second thoughts i'm not even sure the ? is required - the expression can be greedy.

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