I had the same question as the OP, but maybe a different requirement. I created this function...
/**
* Get the base URL of the current page. For example, if the current page URL is
* "https://example.com/dir/example.php?whatever" this function will return
* "https://example.com/dir/" .
*
* @return string The base URL of the current page.
*/
function get_base_url() {
$protocol = filter_input(INPUT_SERVER, 'HTTPS');
if (empty($protocol)) {
$protocol = "http";
}
$host = filter_input(INPUT_SERVER, 'HTTP_HOST');
$request_uri_full = filter_input(INPUT_SERVER, 'REQUEST_URI');
$last_slash_pos = strrpos($request_uri_full, "/");
if ($last_slash_pos === FALSE) {
$request_uri_sub = $request_uri_full;
}
else {
$request_uri_sub = substr($request_uri_full, 0, $last_slash_pos + 1);
}
return $protocol . "://" . $host . $request_uri_sub;
}
...which, incidentally, I use to help create absolute URLs that should be used for redirecting.