- var_dump: documentation ( source)
- mb_detect_encoding: documentation ( source)
<?php
$domains = [
'danielabruña.com',
'xn--fagualpez-b7a.com',
'laconspiracióndelcastellano.com',
];
foreach ($domains as $domain) {
$needs_encoding = mb_detect_encoding($domain, ['ASCII', 'UTF-8'], true) === 'UTF-8';
var_dump($domain, $needs_encoding);
}