PHP 5.1 to PHP 7.1 broke contact form

Question

The web hosting service provider upgraded to PHP 7.1 and it broke the contact form of the page. I've narrowed it down to this piece of code:

function check_email($mail)
{
    $email_host = explode("@", $mail);
    $email_host = $email_host['1'];
    $email_resolved = gethostbyname($email_host);
    if ($email_resolved != $email_host && @eregi("^[0-9a-z]([-_.~]?[0-9a-z])*@[0-9a-z]([-.]?[0-9a-z])*\\.[a-z]{2,4}$",$mail))
    $valid = 1; return $valid;
}

I've found that the eregi function is no longer supported in PHP 7.1 but I dont know how and with what i should replace it.

Answer 1

Have a look at the documentation of eregi function in php.net:

Warning

This function was DEPRECATED in PHP 5.3.0, and REMOVED in PHP 7.0.0.

Alternatives to this function include:

preg_match() (with the i (PCRE_CASELESS) modifier)

You should always have a look there when it comes do deprecated functions.

For validating email addresses you could also use filter_var now:

if (filter_var('test@example.com', FILTER_VALIDATE_EMAIL)) {
    echo "Email valid.";
}