Regex to match 000001 to 002000

Question

I have strings from ~~000001~~ 00000 to 999999.

I'm looking for a regex to capture the 2000 elements, from 000001 to 002000. Maybe the question is too naïve, but after some attemps, I'm not finding the right one...

Could somebody help, please? Thanks!

EDIT: this question has been identified as possible dublicated of this and I have asked to edit the question to explain why it isn't. The aforementioned question is about regex in general but I'm asking for a very specific case (you can argue if the specific case is trivial or not, but that is a different question ;)

Possible duplicate of [Learning Regular Expressions](https://stackoverflow.com/questions/4736/learning-regular-expressions) — Biffen, Sep 05 '18 at 08:17
It would probably be better to convert this to a number and compare... regex _can_ do this, but it's not ideal. — Attie, Sep 05 '18 at 08:18
@Biffen this is not really a duplicate as he is asking for a particular scenario — Juan Carlos Rodriguez, Sep 05 '18 at 08:18
I have tried for instance with `E00(001\d\d\d|2000)` but is not working properly... I'm keep trying, just asking in the case somebody could help. In the case I find the right answer, I'll self-answer myself. — fgalan, Sep 05 '18 at 08:19
https://www.regular-expressions.info/numericranges.html – but it's not pretty. — Stefan, Sep 05 '18 at 08:22
@JuanCarlosRodriguez The linked question is used as a duplicate for all the ‘I need a regex’ questions. — Biffen, Sep 05 '18 at 08:22
I'm not sure this should be closed with a so wide QA. The approach isn't 100% trivial (but there might be an existing closer QA). — Denys Séguret, Sep 05 '18 at 08:28

Denys Séguret · Accepted Answer · 2018-09-05T08:39:17.543

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You may use this one:

^0*(2000|1?[0-9]{3})$

As per your comment, you also want to exclude "000000". Then use

^(?!000000)0*(2000|1?[0-9]{3})$

["000000", "000001", "999999", "001541", "000015", "002000"].forEach(s=> console.log(s, /^(?!000000)0*(2000|1?[0-9]{3})$/.test(s)))

But most real world sane solutions would just parse the number and compare it to a range. This would be less prone to errors and much easier to check and maintain.

edited Sep 05 '18 at 08:39

answered Sep 05 '18 at 08:19

Denys Séguret

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Thanks for the feedback! However, as far as I understand, that regex would match 000000... Note the range to cover is from 000001 to 002000 – fgalan Sep 05 '18 at 08:22
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@fgalan 000000 was excluded from the list of possible inputs in your question – Denys Séguret Sep 05 '18 at 08:23
@fgalan In any case I edited to exclude it in the regex – Denys Séguret Sep 05 '18 at 08:26
My fault, sorry. I have edited the post to explain that 000000 is also parte of the range. Thanks again for your feedback! – fgalan Sep 05 '18 at 08:36
I'd switch the order of lookahead and start-of-the-line in your second regex for a minimal performance boost for non-matching cases. – Sebastian Proske Sep 05 '18 at 08:38
@SebastianProske if input strings are always 6 chars long then there's probably no impact but I agree it can only be better. – Denys Séguret Sep 05 '18 at 08:39

CrafterKolyan · Answer 2 · 2018-09-05T08:25:06.587

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Check this: ^00([01]\d{3}|2000)$

Be careful, it also matches 000000, but as you said there's no such string so everything is ok.

edited Sep 05 '18 at 08:25

answered Sep 05 '18 at 08:18

CrafterKolyan

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Regex to match 000001 to 002000

2 Answers2