Find out the subdomain part of a domain

Use this code to find the subdomain part of a domain.

function SubdomainGet ($domain) {
    // Domain has to be formatted WITHOUT the "http://" part
    // eg.
    //     $domain = 'mydomain.com';

    $server_address = $_SERVER['HTTP_HOST'];

    // Strip the domain and leave the subdomain
    $sub_domain = str_replace("." . $domain, "", $server_address);

    if ($sub_domain == $server_address) {
    $sub_domain = '';
}

return $sub_domain;
}

You could use it like this:

$subdomain = SubdomainGet('example.com');

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