3v4l.org

run code in 300+ PHP versions simultaneously
<?php function getDomain() { return 'example.com'; } function getSubDomains() { return array('www.example.com'); } function register($domainKeys, $subdomains) { $domains = (array) getDomain(); if ($subdomains == null) { $domains = array_merge($domains, getSubdomains()); } else { $domains = array_merge($domains, $subdomains); } return $domains; } var_dump(register(null, []));
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.6 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array(2) { [0]=> string(11) "example.com" [1]=> string(15) "www.example.com" }
preferences:
148.24 ms | 404 KiB | 212 Q