为什么我的电子邮件验证不起作用？ PHP

Question

I have used

if (!preg_match('/[a-z||0-9]@[a-z||0-9].[a-z]/', $email)) {
    [PRINT ERROR]
}

&

if (!eregi( "^[0-9]+$", $email)) {
    [PRINT ERROR]
}

&

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
    [PRINT ERROR]
}

I have also tried taking out the ! and make it work backwards but for some reason NONE of those work to find out if it is valid. Any ideas why?... I have it in an else if statement, Im not sure if that could be the cause..

I am using PHP

Answer 1

Try

'/[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}/'

...

if (!preg_match('/[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}/', strtoupper($email))) {
    [PRINT ERROR]
}

As far as I can see, none of your regex expressions would match an email.