FILTER_VALIDATE_EMAIL出错

Question

For some reasons, that are unclear for me, I can't use this code on my website: when I use it the php form doesn't load.

<?php
$email = "[e-mail]";
$email = (filter_var($email, FILTER_SANITIZE_EMAIL));       
if (!filter_var($email, FILTER_VALIDATE_EMAIL) === false) {
    echo("$email is a valid email address");
} else {
    echo("$email is not a valid email address");
}

This one works but it doesn't give an error when there isn't a . after the @ in the email, so the email below get validated

$email = "john.doe@examplecom";
$email = (filter_var($email, FILTER_SANITIZE_EMAIL));

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    echo("$email is a valid email address");
} else {
    echo("$email is not a valid email address");
}
?>

How can I get my form to validate only email with an @ and a . after the @

Edit:

        $authorEmail = (filter_var($_POST['formEmail'], FILTER_SANITIZE_EMAIL));
        if (!(filter_var($authorEmail, FILTER_VALIDATE_EMAIL))){
            $emailError = true;
            $hasError = true;
        } else{
            $formEmail = $authorEmail;
        };

Answer 1

You shouldn't try to enforce validation that is too strict. your second example ("john.doe@examplecom") is a valid email address according to the relevant RFC standards (5321, 5322 and 6531). Other valid email addresses include:

• "()<>[]:,;@\\"!#$%&'*+-/=?^_`{}| ~.a"@example.org
• user@[IPv6:2001:db8::1]
• user@com

This one has to be posted as code because it contains so many weird characters:

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

examples taken from email wiki

The closest you can get to an RFC compliant home-grown validation system is to use an insanely complex regex: like this one