表单字段验证自定义电子邮件要求

Question

Looking to create a form validation on email text field. Have previously used validation to ensure correct email is produced.

But here looking to create a more custom rule which allows only emails ending in the format .ac.uk

Here a user would be able to provide any university/college/instituion as long as the last 6 characters in the string = .ac.uk with the general format for the mail as follows: [e-mail]

Solution preferably in PHP, currently looking at employing a rule using the end part in this statement:

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

Making this part *(\.[a-z]{2,3}) relate to the .ac.uk

many thanks, much appreciated Jeanclaude

Answer 1

I would first run the email through filter_var($email, FILTER_VALIDATE_EMAIL) rather than using a simple regex. It's not perfect (I've found a few edge cases that don't validate correctly) but it works well. Once you know it's a valid email address you can simply trust substr($email, -6) == '.ac.uk' and be done with it. Something like:

if (filter_var($email, FILTER_VALIDATE_EMAIL) 
    && strtolower(substr(trim($email), -6))) === '.ac.uk') {

    // Valid
}