How create variable as variable for globel

In php 

$id       = 1; //this is changeable 
$var     = 'hello'.$id;

$$var = 'result is here';

echo $$var;   // here var is $hello1
echo $hello1;  // same

works fine in php and codeigniter controller works in  one function only.

1. how to use and update $$var all function with in controller ?

 $$var 
create first function .
update another function .
using another function .

How ??
Thanks.

It would help to know where you are setting these are they Global or in a method?

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )

It would help to know where you are setting these are they Global or in a method?

var is global
using and changing value of var multiple method func.
within one controller