Regex match blank between "--"

Question

I have an issue with a regex. here below details:

I have the following basis chain:
N_aa-AAAA-140143-AAAAAA_1---

The regex i'm using:

^N_([A-Za-z]+)-([A-Za-z]+)-([A-Za-z0-9]+)-([A-Za-z0-9_-éÉ\s]+)---

The result i have for the basis chain:
group1: aa.
group2: AAAA.
group3: 140143.
group4: AAAAAA_1.

But sometimes there is some missing element between "--" for the group3:
N_AA-AA--AAAA_1---

The result i would like in this case:
group1: aa.
group2: AAAA.
group3: blank (nothing).
group4: AAAAAA_1.

Thanks for your help ;-).

Use `*` instead of `+`. – 41686d6564 stands w. Palestine Sep 07 '20 at 18:03 — 41686d6564 stands w. Palestine, Sep 07 '20 at 18:03

score 0 · Accepted Answer · answered Sep 07 '20 at 18:12

If the 3rd group is optional then use the * quantifier (0 or many occurrences) instead of + (at least 1 or many occurrences):

^N_([A-Za-z]+)-([A-Za-z]+)-([A-Za-z0-9]*)-([A-Za-z0-9_-éÉ\s]+)---

See it passing your 2 test-cases here: https://regex101.com/r/DWStTX/1

1 Answers1