Why doesn't my email regex for PHP work?

Question

I have the same expression in Javascript but it won't work in PHP for server side validation. Here's the code

if (ereg('/^([a-zA-Z0-9_.-])+@([a-zA-Z0-9_.-])+\\.([a-zA-Z])+([a-zA-Z])+/',$_POST['email-address']))
    echo "valid email";
else
    echo "invalid email";

Answer 1

I use the following. I also would run TRIM() on the input string before comparing it:

function is_email($string) {
  if (preg_match('/^[^0-9][a-zA-Z0-9_]+([.][a-zA-Z0-9_]+)*[@][a-zA-Z0-9_]+([.][a-zA-Z0-9_]+)*[.][a-zA-Z]{2,4}$/',$string)) {
    return true;
  } else {
    return false;
  }
}

Answer 2

It could be because of the symbol you are using to concatenate the expressions (+).

Anyways you should try this one:

\w+([-+.']\w+)@\w+([-.]\w+).\w+([-.]\w+)*

Answer 3

filter which comes with PHP:

if(!filter_var($email, FILTER_VALIDATE_EMAIL)) {

echo "E-mail is not valid";

} else {

echo "E-mail is valid";

}

Answer 4

Don't use regular expressions to "validate" email addresses

Edit: Link is broken. This is probably the right link

Answer 5

use preg_match, not ereg. ereg regex strings do not use an enclosing slash character.

Also the double-backslash may not be necessary in a single-quoted string in PHP (not sure about that, though)

Answer 6

I've now collated test cases from Cal Henderson, Dave Child, Phil Haack, Doug Lovell and RFC 3696. 158 test addresses in all.

I ran all these tests against all the validators I could find. The comparison is here: http://www.dominicsayers.com/isemail

I'll try to keep this page up-to-date as people enhance their validators. Thanks to Cal, Dave and Phil for their help and co-operation in compiling these tests and constructive criticism of my own validator.

People should be aware of the errata against RFC 3696 in particular. Three of the canonical examples are in fact invalid addresses. And the maximum length of an address is 254 or 256 characters, not 320.