Regex to allow all but the character 0 on its own

Question

I want to create a regex to that will allow numbers and or characters but not 0 (zero) on its own.

This is what I have so far whilst playing with regex101.com

/^([^0])([a-z1-9])*$/img

It matches the last 3 items but I also need it to match the 00 one.

0
00
12
22344
sometext

How can I do this, how can I write "if its 0 on its own I don't want it, but anything else I do want it"?

Reopening because it is not correct dupe as it is not just match everything but specific pattern. Even main body `[a-z1-9]` requires a tweak here. — anubhava, Oct 20 '21 at 15:07
@Daniel: That will also match a single `_` but OP only wanted alphanumeric (as per the attempted regex) — anubhava, Oct 20 '21 at 15:50

score 3 · Accepted Answer · answered Oct 20 '21 at 15:05

3

You can use a negative lookahead to disallow just 0 and then match 1+ alphanumeric in the match to allow matching 0s:

^(?!0$)[a-z\d]+$

(?!0$) is negative lookahead after start position so that we fail the match if just 0 appears in input.
[a-z\d]+ matches 1 or more of a lowercase letter or a digit.

answered Oct 20 '21 at 15:05

anubhava

1

Thanks for that and adding a bit extra explanation, I don't do them enough, but did see it call it a lookahead in regex101, many thanks – Andrew Oct 20 '21 at 15:13

1 Answers1