Regex to find text between a pair of words if the first word does not appear again

Question

I need to capture the string ||EPB|| and |TRN| but only if they appear as a pair.

My text looks like this.

||EPB|| 1-2-3 |TRN| ||EPB||....||EPB|| Other text ||EPB|| 11-2-3 Test A |TRN| more text that may have carriage returns in it ||EPB||nospace/here||EPB|| 12-2-3 |TRN|

I want the results to be:

1-2-3
11-2-3 Test A
12-2-3

The closest I got was \|\|EPB\|\|(.*?)\|TRN\| But that doesn't handle the situation where there is more than one ||EPB|| appears before a |TRN|

Use `\|\|EPB\|\|((?:(?!\|\|EPB\|\|).)*?)\|TRN\|`. Demo: https://regex101.com/r/apXx8P/1 — 41686d6564 stands w. Palestine, Nov 10 '21 at 01:13
Duplicate of: [Regex: match everything but specific pattern](https://stackoverflow.com/questions/1687620/regex-match-everything-but-specific-pattern), [Match everything except for specified strings](https://stackoverflow.com/q/2404010/8967612) — 41686d6564 stands w. Palestine, Nov 10 '21 at 01:15
`(?<=[|]{2}EPB[|]{2})\s*([^|]*?)\s*(?=[|]TRN[|])` [Demo](https://regex101.com/r/00YSLQ/1) — Daniel, Nov 10 '21 at 01:27
I deleted my answer because it was unnecessarily complex when compared to that proposed by @41686d6564 in a comment above. I have therefore deleted it. — Cary Swoveland, Nov 10 '21 at 06:14
@Daniel, your regex does not match `"1-2-|3"` in `"||EPB|| 1-2-|3 |TRN|"`. — Cary Swoveland, Nov 10 '21 at 06:26
@41686d6564, nice one. You could of course avoid the capture group with [lookarounds](https://regex101.com/r/TkelBm/1). — Cary Swoveland, Nov 10 '21 at 06:32
@CarySwoveland, that was intentional. If pipes are the delimiter here then the only `|` that should match is one that is complete as `|TRN|` — Daniel, Nov 10 '21 at 14:21

zimbozim · Answer 1 · 2021-11-24T21:53:04.727

-1

My solution though not perfect is better than the closest you got above.

(?<=||EPB||)(.*?)(?=|TRN|)

It attempts to "wrap" your string between a positive look behind assertion (match ||EPB|| but nothing before it) and a positive look ahead assertion(match |TRN| but nothing after it).

For a regular expression cheat sheet: https://cheatography.com/davechild/cheat-sheets/regular-expressions/

edited Nov 24 '21 at 21:53

answered Nov 10 '21 at 02:14

zimbozim

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As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers [in the help center](/help/how-to-answer). – Community Nov 10 '21 at 04:41
edited again to be more explanatory. – zimbozim Nov 24 '21 at 21:53

Regex to find text between a pair of words if the first word does not appear again

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