Regular expression, find a word between two words

Question

I have this string

<p/><ul><li>test1<p/></li><li>test2<p/></li></ul><p/>

What i attempt to do is extract all the "p" tag within the "li" tag, but not the "p" tag outside of it.

I'm only able so far to extract all the "li" tags by

\<li\>(.*?)\</li\>

I'm lost at how to extract the "p" tag within it.

Any pointer is greatly appreciated it!!

http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags — Yuriy Faktorovich, Mar 05 '10 at 22:29
Parse HTML with an HTML parser. HTML is not a "regular language" and therefore cannot be parsed correctly with a regular expression. — Eric Lippert, Mar 05 '10 at 22:31

score 5 · Answer 1 · answered Mar 05 '10 at 22:32

5

It is a lot more reliable to use an HTML parser instead of a regex. Use HTML Agility Pack:

HtmlDocument doc = new HtmlDocument();
doc.LoadHtml("<p/><ul><li>test1<p/></li><li>test2<p/></li></ul><p/>");
IEnumerable<HtmlNode> result = doc.DocumentNode
                                  .Descendants("li")
                                  .SelectMany(x => x.Descendants("p"));

answered Mar 05 '10 at 22:32

Mark Byers

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Thanks Marks. Actually, I'm parsing bbcode out a bunch of text and after the last iteration of converting bbcode, the text came out like that, so I need to do a bit clean up. But thanks for the suggestion though. – Liming Mar 05 '10 at 22:51

score 2 · Answer 2 · answered Mar 05 '10 at 22:29

2

<li>(.*?<p/?>.*?)</li>

Will match all content between <li> which also contain a <p/>. If you just want to match the <p/> then:

(?<=<li>).*?(<p/?>).*?(?=</li>)

Will have group 1 match the <p/> tag.

answered Mar 05 '10 at 22:29

Pindatjuh

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You and James are Regx Nija! Thanks a lot – Liming Mar 05 '10 at 22:49

score 2 · Accepted Answer · answered Mar 05 '10 at 22:35

Try this, it uses lookahead so that the LI is not part of the selection.

(?<=<li>)(.*?<p/?>.*?)(?=</li>)

P.S. You also need to fix your HTML because the way you have P tags is not right. The Regex works on this HTML below.

<ul><li><p>test1<p/></li><li><p>test2<p/></li></ul>

Regular expression, find a word between two words

3 Answers3