Is this proper regular expression behaviour?

[therks 31]

So I have this pattern: 

^(?:(\d+)|(\d+):(\d+)|(\d+):(\d+):(\d+))$

And I'm expecting (depending on input) to get a 1, 2 or 3 index array (or @error for invalid input).

But instead I get this:

#include <Debug.au3>

Func Test($String)
    _DebugArrayDisplay(StringRegExp($String, '^(?:(\d+)|(\d+):(\d+)|(\d+):(\d+):(\d+))$', 1))
EndFunc

Test('10')
; Results (normal, expected):
; Row 0|10

Test('10:20')
; Results (extra blank index):
; Row 0|
; Row 1|10
; Row 2|20

Test('10:20:30')
; Results (three blank indices):
; Row 0|
; Row 1|
; Row 2|
; Row 3|10
; Row 4|20
; Row 5|30

Is this normal? Should I just code around it, or is there a better way to do what I'm looking for?

I also tried reversing my regex, but it was even uglier results:

#include <Debug.au3>

Func Test($String)
    _DebugArrayDisplay(StringRegExp($String, '^(?:(\d+):(\d+):(\d+))|(\d+):(\d+)|(\d+)$', 1))
EndFunc

Test('10')
; Results (yuck):
; Row 0|
; Row 1|
; Row 2|
; Row 3|
; Row 4|
; Row 5|10

Test('10:20')
; Results (slightly better):
; Row 0|
; Row 1|
; Row 2|
; Row 3|10
; Row 4|20

Test('10:20:30')
; Results (nice):
; Row 0|10
; Row 1|20
; Row 2|30

 

[mikell 1,007]

In your first expression, just change this  ?:  to this  ?| 
and please refer to the helpfile for explanations 

[therks 31]

Oh so that's what it means. I thought resetting meant I would lose my captures or something so I never even tried it. Thanks!