CODEWITHSUNDEEP
phpregex
user482520
user482520

Reputation: 77

Regex Expressions: Filter Email addresses

I have the following regex expression 

/^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/

that currently matches email addresses of the form [email protected] (do not want this email address to be accepted bc it starts with a hyphen) If I want it to reject email addresses that start with a - (hyphen) and only accept those that start with an underscore _ how would I modify the regex?

Another question before modifying the regex -- can emails even start with hyphens? If they can, then there's no point in modifying the regex.

Thanks.

Upvotes: 0

Views: 871

Answers (4)

nachito
nachito

Reputation: 7035

[email protected] is a valid email address.

From RFC3696 Section 3: Restrictions on email addresses:

local-parts may consist of any combination of alphabetic characters, digits, or any of the special characters

  ! # $ % & ' * + - / = ?  ^ _ ` . { | } ~

It may be interesting to note also that "[periods] may not be used to start or end the local part, nor may two or more consecutive periods appear."

Upvotes: 2

mario
mario

Reputation: 145482

To find out if email addresses with leading - hyphens are allowed, you could use a more standards-compliant regex to check:

print filter_var("[email protected]", FILTER_VALIDATE_EMAIL);

Upvotes: 2

Naftali
Naftali

Reputation: 146302

Just fix the 1st part of your regex:

/^[_a-zA-Z0-9]+(\.[_a-zA-Z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/

Upvotes: 0

JoshStrange
JoshStrange

Reputation: 1129

/^[_a-zA-Z0-9]+(\.[_a-zA-Z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/

Upvotes: 2

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