Easily pull the segment of a URL without constantly re-writing code. Documentation here: http://gearside.com/php-function-easily-return-url-components/

gearside_url_components.php

//Get the full URL. Not intended for secure use ($_SERVER var can be manipulated by client/server).
function gearside_requested_url($host="HTTP_HOST") { //Can use "SERVER_NAME" as an alternative to "HTTP_HOST".
	$protocol = ( (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off') || $_SERVER['SERVER_PORT'] == 443 ) ? 'https' : 'http';
	$full_url = $protocol . '://' . $_SERVER["$host"] . $_SERVER["REQUEST_URI"];
	return $full_url;
}


//Separate a URL into it's components.
//See http://gearside.com/php-function-easily-return-url-components/ for documentation
function gearside_url_components($segment="all", $url=null) {
	if ( !$url ) {
		$url = nebula_requested_url();
	}

	$url_compontents = parse_url($url);
	if ( empty($url_compontents['host']) ) {
		return;
	}
	$host = explode('.', $url_compontents['host']);

	//Best way to get the domain so far. Probably a better way by checking against all known TLDs.
	preg_match("/[a-z0-9\-]{1,63}\.[a-z\.]{2,6}$/", parse_url($url, PHP_URL_HOST), $domain);
	$sld = substr($domain[0], 0, strpos($domain[0], '.'));
	$tld = substr($domain[0], strpos($domain[0], '.'));

	switch ($segment) {
		case ('all') :
		case ('href') :
			return $url;
			break;

		case ('protocol') :
		case ('scheme') :
		case ('schema') :
			if ( $url_compontents['scheme'] != '' ) {
				return $url_compontents['scheme'];
			} else {
				return false;
			}
			break;

		case ('host') :
		case ('hostname') :
			return $url_compontents['host'];
			break;

		case ('www') :
			if ( $host[0] == 'www' ) {
				return 'www';
			} else {
				return false;
			}
			break;

		case ('subdomain') :
		case ('sub_domain') :
			if ( $host[0] != 'www' && $host[0] != $sld ) {
				return $host[0];
			} else {
				return false;
			}
			break;

		case ('domain') :
			return $domain[0];
			break;

		case ('basedomain') :
		case ('base_domain') :
		case ('origin') :
			return $url_compontents['scheme'] . '://' . $domain[0];
			break;

		case ('sld') : //In example.com the sld is "example"
		case ('second_level_domain') :
		case ('second-level_domain') :
			return $sld;
			break;

		case ('tld') : //In example.com the tld is ".com"
		case ('top_level_domain') :
		case ('top-level_domain') :
			return $tld;
			break;

		case ('filepath') :
		case ('pathname') :
			return $url_compontents['path'];
			break;

		case ('file') :
		case ('filename') :
			if ( contains(basename($url_compontents['path']), array('.')) ) {
				return basename($url_compontents['path']);
			} else {
				return false;
			}
			break;

		case ('extension') :
		    if ( contains(basename($url_compontents['path']), array('.')) ) {
		        $file_parts = explode('.', $url_compontents['path']);
		        return $file_parts[1];
		    } else {
		        return false;
		    }
		    break;

		case ('path') :
			if ( contains(basename($url_compontents['path']), array('.')) ) { //Note: This can possibly give bad data if the directory name has a "." in it
				return str_replace(basename($url_compontents['path']), '', $url_compontents['path']);
			} else {
				return $url_compontents['path'];
			}
			break;

		case ('query') :
		case ('queries') :
		case ('search') :
			return $url_compontents['query'];
			break;

		default :
			return $url;
			break;
	}
}