how to pass empty variable into url?

[eluser]Unknown[/eluser]
hello..

i've create a class with index function like this

Code:

class Myclass extends Controller
{
function Myclass()
{
  parent::Controller();
}

function index($var1="",$var2="",$var3="",$var4="")
{
  .... bla bla bla
}
}

this URL is working the way i wanted:
http://blabla.com/codeigniter/myclass/in...3/content4

but with this url, i can't get var4 value
http://blabla.com/codeigniter/myclass/index////content4

why is that happen? any solution?

sorry for my poor english