how does this preg_match check for email validation?

Question

I have a function (that works) and checks if an email address is valid. I understand how most of it is working except for the part that actually tests when there is a decent looking email.

How does this work:

 if ( 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])?/i", $email) ) {
        $valid_address = true;
      } else {
        $valid_address = false;
      }
    }

I don't really understand preg_match, so this looks like pretty much random characters.

If you think that regex is bad, try the [RFC-compliant one](http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html) on for size. Heh. — ceejayoz, Jul 12 '13 at 14:17

score 4 · Accepted Answer · answered Jul 12 '13 at 14:13

4

Don't use preg_match to validate e-mails. PHP has a built in function for this.

filter_var('bob@example.com', FILTER_VALIDATE_EMAIL)

That said, preg_match's operators are well documented.

answered Jul 12 '13 at 14:13

ceejayoz

171,474
40
284
355

Cool. Did not know that existed. This is part of a larger project (oscommerce) but I can pretty easily change it over. – Sackling Jul 12 '13 at 14:14

score 1 · Answer 2 · edited May 23 '17 at 12:06

1

First, preg_match has documentation here: http://php.net/manual/en/function.preg-match.php

but what it sounds like you really want to know is regular expressions(that string of crazy characters): Learning Regular Expressions

The second answer has a decent overview.

edited May 23 '17 at 12:06

Community

1
1

answered Jul 12 '13 at 14:17

Snagulus

132
5

how does this preg_match check for email validation?

2 Answers2