Match all words with a specific length

Question

I want to make a regex that matches all words with a specific length.
Example of the string I have: "I ABCDE FGH IG KLMNOPQ RS T"
I want to match all words having length less than 3 letters (In this case I, IG, RS and T).
Here are the alternatives that I made:
Alt1:
Regex: ( |^)([A-Z]{1,2})( |$): Link1
Explanation: Matching any word with a length of 2 or 1 uppercase letters that is preceded by a space or in the beginning of the string (( |^)) and followed by a space or at the end of the string (( |$)).

The problem is that I get positive match for the blank spaces which I don't want. And I don't get match for the T.
Alt2:
Regex: \w{1,2}\b: Link2
Explanation:

match a word of at most 2 characters as long as its the only contents of the string
(I found it in this answer)

The problem is that I get matches of every last 2 letters from every word (DE, GH and PQ) which is wrong in my case.

Do you mean `(?<!\S)[A-Z]{1,2}(?!\S)`? https://regex101.com/r/ykA3r0/1 — The fourth bird, Jul 08 '19 at 17:11
That literately does what I wanted. Would you please post an answer with some explanation. Thank you! — singrium, Jul 08 '19 at 17:13

score 1 · Accepted Answer · answered Jul 08 '19 at 17:12

1

You're close! Just add a \b boundary to the front as well:

\b\w{1,2}\b

Matches:

I ABCDE FGH IG KLMNOPQ RS T
~           ~~         ~~ ~

answered Jul 08 '19 at 17:12

ggorlen

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Thank you it is working! – singrium Jul 08 '19 at 17:13

score 1 · Answer 2 · answered Jul 08 '19 at 17:16

If you have to take the whitespaces into account, you could match 1 or 2 uppercase digits and use lookarounds to assert what is directly on the left and on the right is not a non whitspace char \S

If the uppercase characters are surrounded by for example$AB# they will not be matched.

(?<!\S)[A-Z]{1,2}(?!\S)

Regex demo

Match all words with a specific length

2 Answers2