Regular Expression to capture the first
of HTML

Question

I have the following regular expression:

(?:<(?<tag>\w*)>(?<text>.*)</\k<tag>>)

I want it t grab the text within the first HTML element.

eg.

<p>This should capture</p>This shouldn't

Works, but ...

<p>This should capture</p><p>This shouldn't</p>

Doesn't work. As you'd expect, it returns:

This should capture</p><p>This shouldn't

I'm racking my brains here. How can I just have it select the FIRST inner text?

(I'm trying to be tag-agnostic, so <strong>This should match</strong> is equally appropriate, etc.)

And there was me thinking I should do that instead of building a state machine. Any reason why? — Program.X, Jun 03 '10 at 15:42
See this answer to a similar question: http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 — Sarah Vessels, Jun 03 '10 at 15:43
http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 — SLaks, Jun 03 '10 at 15:43
Fair enough. I know what you're saying, I just wanted the first bit of text so I didn't anticipate parsing an extensive document. Thanks. — Program.X, Jun 03 '10 at 15:46
@Program: And what do you expect to do in the case of `
text
more text
`? You can't keep track of arbitrary nesting like this using RegEx. — BlueRaja - Danny Pflughoeft, Jun 03 '10 at 15:52

score 3 · Accepted Answer · answered Jun 03 '10 at 15:41

3

You should use the HTML Agility Pack.

For example:

doc.DocumentNode.Descendants("p").First().InnerText

answered Jun 03 '10 at 15:41

SLaks

1

I actually am looking at using the HtmlAgilityPack for another section of the project so this is "on the radar". I might just use it in the longer term. – Program.X Jun 03 '10 at 15:52

score 2 · Answer 2 · edited May 23 '17 at 11:55

2

Stop. Just stop. If you are parsing HTML, use an HTML parser (or XML if you're dealing with valid XHTML). See this answer for more info.

edited May 23 '17 at 11:55

Community

answered Jun 03 '10 at 15:42

Hank Gay

score 1 · Answer 3 · answered Jun 03 '10 at 15:42

1

In order to have a non-greedy * selection, you should add an ? after the *.

(?:<(?<tag>\w*)>(?<text>.*?)</\k<tag>>)

answered Jun 03 '10 at 15:42

HoLyVieR

Thanks. I'm going to go for that only because it is very simple work I am doing and I am coping with failure elegantly. Then again @BlueRaja has just blown a hole in my theory. Sorry. – Program.X Jun 03 '10 at 15:51

3 Answers3