What does regular expression [A-Z]{2,3}\\d+ mean

Question

What does the regex [A-Z]{0,2,3}\\d+ mean?

Does it match strings like

AAA1234 0000123 AA12345

Thanks

Do you mean [`[A-Z]{0,3}\\d+`](https://regex101.com/r/6K8Txf/1)?`{0,3}` will match and uppercase character 0 - 3 times. — The fourth bird, Jun 11 '18 at 17:48
[Reference Q&A](https://stackoverflow.com/q/22937618/335858) — Sergey Kalinichenko, Jun 11 '18 at 17:48
Long story short, your regex would match `A{0,2,3}1234` strings ([demo](https://regex101.com/r/lga72J/1)). — Sergey Kalinichenko, Jun 11 '18 at 17:52
You may find the [Regex101](https://regex101.com/r/fdoCIc/1) online tool beneficial to try this out yourself, and play around with regular expressions. Just put the regex in the top and not only will it explain what each part does when you hover, but it will let you try different input strings below to see what works and what doesn't. — Callum Watkins, Jun 11 '18 at 18:04
@dasblinkenlight - Not really, it would match `A{0,2,3}\ddd` — , Jun 11 '18 at 18:24

Pranay Majmundar · Accepted Answer · 2018-06-11T18:00:35.037

4

[A-Z]{0,2,3}\\d+

That looks like a typo.

{} braces shouldn't have more than two numbers in it.

[A-Z]{0,3} mean any alphabet between A and Z (capital) can occur 0 to 3 times.

And \d+ means any digit (0-9) can occur 1 or more times.

That is the reason [A-Z]{0,3}\d+ matches AAA1234, 0000123 and AA12345

edited Jun 11 '18 at 18:00

answered Jun 11 '18 at 17:55

Pranay Majmundar

OP's syntax is valid and compiles fine. The OP's regex matches the input string `A{0,2,3}1`. It is true that it's likely a typo, however. – ggorlen Jun 11 '18 at 17:57
Thanks, that makes sense yes the {} was wrong it should have been [A-Z]{2,3}\\d+, I had to add another exception for only characters so my new string looks like: [A-Z]{2,3}\\d+|\\d{7} which has 2 or 3 characters in caps, with lagging digits or digits which are limited to 7 – Uska Jun 11 '18 at 18:00
right, ggorlen... Adjusted my answer – Pranay Majmundar Jun 11 '18 at 18:01
The backslash before the `d` is escaped, so it doesn't mean a digit... right? – Callum Watkins Jun 11 '18 at 18:05
In `[A-Z]{2,3}\d+|\d{7}`, with regards to `lagging digits or digits which are limited to 7 `; `\d+` is a subset of `\d{7}`; i.e.: anything matched by `\d{7}` will also be matched by `\d+`. This makes `\d{7}` redundant. – Pranay Majmundar Jun 11 '18 at 19:19

Callum Watkins · Answer 2 · 2018-06-11T18:20:56.967

0

Your regex ([A-Z]{2,3}\\d+) will match

edited Jun 11 '18 at 18:20

answered Jun 11 '18 at 18:12

Callum Watkins

@Uska Please use the `edit` button underneath your question to correct the mistake you made so that it is clear what you are asking. – Callum Watkins Jun 11 '18 at 18:13
Done, thanks for the clarification everyone. – Uska Jun 11 '18 at 18:19
The backslash is just escapted – Yassin Hajaj Jun 11 '18 at 18:23
@YassinHajaj I covered that in my answer, what else do you mean? – Callum Watkins Jun 11 '18 at 18:24
@CallumWatkins What I mean is that it will NOT match a backslash since the backslash is just used to escape the second one. – Yassin Hajaj Jun 11 '18 at 18:32
@YassinHajaj but... it will. If there is a mistake in the question that is not my problem. – Callum Watkins Jun 11 '18 at 18:32
@CallumWatkins Indeed you're right.. But it would have been a plus to correct it.. Since OP has provided some samples – Yassin Hajaj Jun 11 '18 at 18:33
@YassinHajaj the samples given are not what the regex *should* match, but OP's original thought of what the regex *might* match. I'm simply stating the facts, rather than answering a question that was not asked. – Callum Watkins Jun 11 '18 at 18:35

2 Answers2