Question on Regular Expression - "optional" group

[Rincevent]

Hi,
I'm trying to process a large number of files, each with a very small size (about 500 chars maximum).
I need to retrieve multiple information from each file, and some of these are optional.
So to "simplify" the process, I undefed $/ (variable contains the full file).

The current regular expression that I know works (with all mandatory matches) is the following:
/\{2:[^\}]+(\d{6})\d{4}.\}.*^:25:(.+?$).*^:13D:(\d{6})/sm
as can be seen, there are 3 groups,
the part I wish to make optional is ^:13D:(\d{6})
so I thought just putting (^:13D:(\d{6}))? would be fine (managing the additional group afterwards of course),
but trying out the changed regular expression:
/\{2:[^\}]+(\d{6})\d{4}.\}.*^:25:((.+?$).*^:13D:(\d{6}))?/sm
it seems the last part never contains anything, even when the previous version did manage a match.
Can someone tell me why?
Also, if my approach is not efficient, any comment on how to better do it will be greatly appreciated. :)

Thanks in advance.

P.S.: I've been trying the script on windows [5.8.8] and unix (aix) [5.8.2],

[Rincevent]

Ok, I kept playing around, and it seems I made 2 mistakes: :p

1/ the "changed" regular expression i presented had a typo (doesn't help when you ask for help not to provide what you used exactly

2/ i made in my first attempts this part of the regular expression optional: ^:13D:(\d{6}), while I should have gone for this one: ..*^:13D:(\d{6})
Problem was the "greedy nature of .*.

So, problem solved. :)

[KevinADC]

Glad you solved it. Next time post some sample data too, that always helps when trying to help with pattern matching that is a bit complex.

[Rincevent]

Thanks for the recommendations, KevinADC.
duly noted. :)