include & URL variables issue

[catalinus]

Facts: I have 3 levels of pages nested one into another:
1st level: index.php
2nd level: header.php, body.php, footer.php
On the body php i have the menu with different options (lets call them aboutus, contactus)
3rd level: aboutus.php, contactus.php
For security reasons I have created functions in the 2nd and the 3rd level pages, to display them, so they are displayed in the parent page by invoking these functions.
The menu on the body.php page is rather programatically, it looks something like this:

if (isset($GET['menu_option'])) {
$menu_option = (get_magic_quotes_gpc()) ? $GET['menu_option'] : addslashes($_GET['menu_option']);
}
else {
$menu_option = "some_default_page.php";
}

switch ($menu_option) {
case "aboutus":
include("./aboutus/aboutus.php");
ShowAboutUs();
break;
case "contactus":
include("./aboutus/aboutus.php");
ShowContactUs();
break;
default:
include("some_default_page.php");
ShowSomeDefaultPage();
}

ShowAbousUs(), ShowContactUs(), ShowSomeDefaultPage() are the functions to call these pages, functions i have just told you about.

My problem is as it follows:
If I want to make a call from a 3rd level page (lets say contactus.php) to another 3rd level page (lets say 3rdlevelpage.php) i receive nothing. I have changed the menu script, adding the following code:
case "3rdlevelpage":
include("./3rdlevelpage.php");
Show3rdLevelPage();
break;
, and also checked the paths and everything
So for instance if i have on contact.php a hyperlink like index.php?menu_option=3rdlevelpage, index.php displays only the header.php, a bit of body.php and nothing from footer.php.

The problem is i guess due to the way i pass the URL variables from one page to another (the parent). I should have hyperlinks like index.php?menu_option=1&submenu_option=2. If i am right, how can i do this in php?

Thanks in advance,
Catalin

[DigitalExpl0it]

this seems to work fine for me

<?
if (isset($_REQUEST['menu_option'])) {
	$menu_option = (get_magic_quotes_gpc()) ? $_GET['menu_option'] : addslashes($_GET['menu_option']);
} else {
	$menu_option = "some_default_page.php";
} 

switch ($menu_option) {
case "aboutus":
	include("aboutus/aboutus.php");
	ShowAboutUs();
	echo "aboutus: ".$menu_option;
	break;
case "contactus":
	include("aboutus/contactus.php");
	ShowContactUs();
	echo "contactus: ".$menu_option;
	break;
default:
	include("some_default_page.php");
	ShowSomeDefaultPage();
	echo "Default: ".$menu_option;
} 
?>

just did this

http://127.0.0.1/switch.php?menu_option=aboutus

if you dont want to pass thru url, make a form and past it that way

[catalinus]

Yes, it works, but only for calls from pages in the 2nd level to pages in the 2nd level or in the 3rd level. But if you make a call from a page on the 3rd level to another page to the 3rd level, it does not work.
I believe that the problem is in building the URL : i should get something like index.php?menu_option=contactus.php&submenu_option=3rdlevelpage.php. An i only can get index.php?menu_option=3rdlevelpage.php. Which of course it doesnt work.