About class upload and multiple image input

[eluser]Rubiz'[/eluser]
Hi all!!

I have a form that is working ok, I'm working with fields in format of arrays just like "work[]", and "images[]" for example.

My question is about using the upload class with this kind of array field.
I'm trying to do this:

Code:

$field_name = 'userfile[' . $i . ']';                    
if ( ! $this->upload->do_upload($field_name))
...

in a for looping, but its not working...

I'll have to name "userfile1", "userfile2", "userfile3" the inputs?