regular expression for excluding between

Question

I have the following regular expression:

first.*(?<!.*([;,\.]|and).*)second

I would like it to match the following:

first some word second

But not match the following:

first . some word second

first ; some word second

It is working but it is also excluding the following:

blah ; first some word second

I only want it to exclude matches if the negative look ahead falls in between the two words. It should not look behind the first word.

Did any of the answers help you? – Wiktor Stribiżew Sep 24 '21 at 07:48 — Wiktor Stribiżew, Sep 24 '21 at 07:48

score 1 · Answer 1 · answered Aug 29 '18 at 15:54

1

You can simply use:

first\b[^.;]*\bsecond

answered Aug 29 '18 at 15:54

blhsing

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score 0 · Answer 2 · answered Aug 29 '18 at 16:35

First, you are not using a lookahead, in your pattern, you are using a lookbehind with an unknown width pattern inside. You want to match a string between a and b excluding c, and this is a common scenario for a tempered greedy token:

first(?:(?!and)[^;,.])*second

See the regex demo. Use word boundaries to match whole words: \bfirst\b(?:(?!\band\b)[^;,.])*\bsecond\b.

Details

first - a literal substring
(?:(?!and)[^;,.])* - zero or more chars other than ;, , and . that do not start an and char sequence
second - a literal substring.

regular expression for excluding between

2 Answers2