CODEWITHSUNDEEP
regex
squill25
squill25

Reputation: 1208

Regex negative lookbehind max "length"

It actually does work.

I am trying to use Regex to match strings with one character surrounded by single quotes ' where both quotes cannot be preceded by a backslash \.

This is my Regex:

(?<!\\)'(.{1})(?<!\\)'

It uses negative lookbehind to ensure that the quotes are not preceded by a backslash.

So far, it works great, but I've run into a certain problem:

From 'H'ello world! it matches 'H', and from \'H'ello world it doen't match 'H' because the 'H' is preceded by \.

The problem I run into is that if I have this string:

'I' have \'r'eally bad 'e'xamples

it will match 'I' because it is not preceded by \, it won't match \'r' because it is preceded by \, but it won't match 'e' because it is not directly preceded by \ but there is an occurrence of \ before that (before 'r').

So my question is, is there any way to specify a "maximum distance" that the negative lookbehind should look for the \?

Thanks in advance!

Upvotes: 2

Views: 491

Answers (1)

Bohemian
Bohemian

Reputation: 425348

Firstly, your look behind is not variable length; it has length exactly 1, because it has only one character.

Secondly, you only need one look behind; the second one is not needed if the dot doesn't match a backslash.

Your regex can be simplified to:

(?<!\\)'[^\\]'

Upvotes: 1

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