Email validation using regular expression in PHP

Question 1

I am pretty much new with regular expression. I am developing a project in PHP and i need to validate email address. After searching in this site and google i found the following regular expression says it should work best.

if (preg_match("/^(?!(?:(?:x22?x5C[x00-x7E]x22?)|(?:x22?[^x5Cx22]x22?)){255,})(?!(?:(?:x22?x5C[x00-x7E]x22?)|(?:x22?[^x5Cx22]x22?)){65,}@)(?:(?:[x21x23-x27x2Ax2Bx2Dx2F-x39x3Dx3Fx5E-x7E]+)|(?:x22(?:[x01-x08x0Bx0Cx0E-x1Fx21x23-x5Bx5D-x7F]|(?:x5C[x00-x7F]))*x22))(?:.(?:(?:[x21x23-x27x2Ax2Bx2Dx2F-x39x3Dx3Fx5E-x7E]+)|(?:x22(?:[x01-x08x0Bx0Cx0E-x1Fx21x23-x5Bx5D-x7F]|(?:x5C[x00-x7F]))*x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))]))$/iD", strtolower($mail_address))) {
    echo "valid email";
}

But when I use it I get error says,

"Warning: preg_match(): No ending delimiter '/' found"

What is wrong with this code?

Question 2

Use this instead of a regular expression:

if(filter_var($email, FILTER_VALIDATE_EMAIL)) {
     //Valid email!
}

Using regular expressions to validate email addresses is not recommended as it is certainly not pretty, especially if you don't want to exclude somebody who has a valid email address that is correct according to RFC 822 grammar.

http://www.php.net/filter_var is your best bet.

A crazy example of a regex that attempts to validate email addresses according to RFC 822 grammar:

(?:(?:rn)?[ t])*(?:(?:(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t]
)+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:
rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(
?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ 
t]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-
31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*
](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+
(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:
(?:rn)?[ t])*))*|(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z
|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)
?[ t])*)*<(?:(?:rn)?[ t])*(?:@(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:
rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[
 t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)
?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t]
)*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[
 t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*
)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t]
)+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*)
*:(?:(?:rn)?[ t])*)?(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+
|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:r
n)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:
rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t
]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31
]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](
?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?
:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?
:rn)?[ t])*))*>(?:(?:rn)?[ t])*)|(?:[^()<>@,;:\".[] 00-31]+(?:(?
:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?
[ t]))*"(?:(?:rn)?[ t])*)*:(?:(?:rn)?[ t])*(?:(?:(?:[^()<>@,;:\".[] 
00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|
\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>
@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"
(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t]
)*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\
".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?
:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[
]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*|(?:[^()<>@,;:\".[] 00-
31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(
?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)*<(?:(?:rn)?[ t])*(?:@(?:[^()<>@,;
:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([
^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\"
.[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[
]r\]|\.)*](?:(?:rn)?[ t])*))*(?:,@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".
[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]
r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 
00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]
|\.)*](?:(?:rn)?[ t])*))*)*:(?:(?:rn)?[ t])*)?(?:[^()<>@,;:\".[] 
00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?:[^"r\]|\
.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[^()<>@,
;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]]))|"(?
:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*))*@(?:(?:rn)?[ t])*
(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".
[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t])*(?:[
^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[]
]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*>(?:(?:rn)?[ t])*)(?:,s*(
?:(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\
".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(
?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[
["()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t
])*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t
])+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?
:.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|
Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*|(?:
[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".[
]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)*<(?:(?:rn)
?[ t])*(?:@(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["
()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)
?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>
@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*(?:,@(?:(?:rn)?[
 t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,
;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:.(?:(?:rn)?[ t]
)*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\
".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*)*:(?:(?:rn)?[ t])*)?
(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[["()<>@,;:\".
[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])*)(?:.(?:(?:
rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z|(?=[[
"()<>@,;:\".[]]))|"(?:[^"r\]|\.|(?:(?:rn)?[ t]))*"(?:(?:rn)?[ t])
*))*@(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])
+|Z|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*)(?:
.(?:(?:rn)?[ t])*(?:[^()<>@,;:\".[] 00-31]+(?:(?:(?:rn)?[ t])+|Z
|(?=[["()<>@,;:\".[]]))|[([^[]r\]|\.)*](?:(?:rn)?[ t])*))*>(?:(
?:rn)?[ t])*))*)?;s*)

Question 3

Using regular expression to validate emails is tricky

Try the following email as an input to your regex ie:^[w.-]+@[A-Za-z0-9.-]+.[A-Za-z]{2,6}$

abc@b...com

You can read more about email regex validation at http://www.regular-expressions.info/email.html

If you are doing this for an app then use email validation by sending an email to the address provided rather than using very complex regex.

Question 4

Use the regex <?([^<]+?)@ then get the result from $matches[1].

Here's what it does:

<? matches an optional <.
[^<]+? does a non-greedy match of one or more characters that are not ^ or <.
@ matches the @ in the email address.

A non-greedy match makes the resulting match the shortest necessary for the regex to match. This prevents running past the @.

Rubular: http://www.rubular.com/r/bntNa8YVZt

Question 5

Here is how:

Using it myself...

<h:inputText id="email" value="#{settingsBean.aFriendEmail}" required="true" label="Email" validatorMessage="#{settingsBean.aFriendEmail} is not valid">
    <f:validateRegex pattern="[w.-]*[a-zA-Z0-9_]@[w.-]*[a-zA-Z0-9].[a-zA-Z][a-zA-Z.]*[a-zA-Z]" />
</h:inputText>
<p:message for="email" />

Daniel.

Question 6

Problem is with the regex format given. Give it without quotes (') like this

regexp = new RegExp(/^(([^<>()[]\.,;:s@"]+(.[^<>()[]\.,;:s@"]+)*)|(".+"))@(([[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}])|(([a-zA-Z-0-9]+.)+[a-zA-Z]{2,}))$/);

Email validation using regular expression in PHP

Answers

php,regex,email