Regex match everything between two string, spaning multiline

Question

How do I regex match everything that is between two strings? The things between two strings span several lines and can contain all html characters too.

For example:

<p>something</p>

<!-- OPTIONAL -->

<p class="sdf"> some text</p>
<p> some other text</p>

<!-- OPTIONAL END -->

<p>The end</p>

I want to strip the whole optional part off. but the greedy any character match isn't doing what I wanted.. the pattern I'm using is

.*
(.*)
(.*)\s+
(?=)(.*)\s+

All of them match the first optional tag, if only the first part is given, but doesn't do well with complete lines.

Here's an example: http://regexr.com?352bk

Thanks

You should not use a regex. http://stackoverflow.com/q/1732348/34397 — SLaks, May 30 '13 at 15:31
@rednaw: 1) Yes; XML uses the same comment syntax. 2) http://htmlagilitypack.codeplex.com — SLaks, May 30 '13 at 15:34
@SLaks how would you strip the optional part out and return every thing else? — LocustHorde, May 30 '13 at 16:27

gitaarik · Answer 1 · 2013-05-30T15:51:48.940

8

To make a regex ungreedy, use a ? after the *:

<!-- OPTIONAL -->(.*?)<!-- OPTIONAL END -->

Does this help you?

Also depending on your programming language you use, you have modifiers that will make your regex dot (.) match newlines too. For PHP you have the s (dotall) modifier for example:

http://php.net/manual/en/reference.pcre.pattern.modifiers.php

edited May 30 '13 at 15:51

answered May 30 '13 at 15:34

gitaarik

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Multiline isn't what the OP needs, but the dotall one. Multiline will make the `^$` anchors match multiple lines instead of a single one. – sp00m May 30 '13 at 15:37
Good one, modified my answer – gitaarik May 30 '13 at 15:52

sp00m · Accepted Answer · 2013-05-30T15:35:21.640

7

Check the dotall checkbox in RegExr :)

Without the dotall flag (the s in /regex/s), a dot (.) won't match carriage returns.

You should use .*? instead of .* to lazy match the optional content (see the PLEASE DO NOT MATCH! sentence in the examples).

edited May 30 '13 at 15:35

answered May 30 '13 at 15:30

sp00m

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Aah! what is dotall, and what does it do, please? – LocustHorde May 30 '13 at 15:31
@LocustHorde By default the wildchard character in regex (`.`) doesn't match newline characters, meaning that the regex stops searching at the end of the line. By enabling dotall the `.` will also include the newline characters in its match. – Bad Wolf May 30 '13 at 15:35

score 4 · Answer 3 · answered Jun 30 '15 at 23:20

4

playing with your example I think I found the answer, check this in your code:

<!-- OPTIONAL -->[\w\W]*<!-- OPTIONAL END -->

I'll hope this help

answered Jun 30 '15 at 23:20

Mauricio Damián Araoz

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I added "?" to the end to make less greedy: ```[\w\W]*?``` – Giddy Naya Feb 20 '22 at 20:00

score 2 · Answer 4 · answered May 30 '13 at 15:30

2

Enable the "dotall" option so that the . in regex will match newline characters and work across multiple lines. There are various ways to do this depending on your implementation of regex, check the manual for your implementation.

answered May 30 '13 at 15:30

Bad Wolf

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Regex match everything between two string, spaning multiline

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