PHP Get Site URL Protocol - http vs https

I've written a little function to establish the current site url protocol but I don't have SSL and don't know how to test if it works under https. **Can you tell me if this is correct?** function siteURL() { $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://"; $domainName = $_SERVER['HTTP_HOST'].'/'; return $protocol.$domainName; } define( 'SITE_URL', siteURL() ); **Is it necessary to do it like above or can I just do it like?:** function siteURL() { $protocol = 'http://'; $domainName = $_SERVER['HTTP_HOST'].'/' return $protocol.$domainName; } define( 'SITE_URL', siteURL() ); Under SSL, doesn't the server automatically convert the url to https even if the anchor tag url is using http? Is it necessary to check for the protocol? Thank you!