XPath to parse invalid HTML in .NET 4.0?

Question

Is it possible to use XPath with .NET, without using any external libraries? Is it natively supported, and can it parse "invalid HTML" (such as tags not being closed etc)?

I would really hate to have to use regular expressions for this, as clearly stated here: RegEx match open tags except XHTML self-contained tags

I've also had bad experiences with regular expressions when it comes to HTML parsing.

score 8 · Accepted Answer · edited Nov 24 '17 at 18:17

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Yes, XPath is natively supported. No, it will not parse tag soup. You'll probably want to use the HTML Agility Pack for that instead.

edited Nov 24 '17 at 18:17

SpruceMoose

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answered Dec 25 '10 at 23:33

Jeff Hubbard

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I've tried the agility pack several times, but it is not compatible with the XPath generated by Google Chrome, or Firefox's Firebug addon. How come? – Mathias Lykkegaard Lorenzen Dec 26 '10 at 00:00
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Because tag soup is not valid XML. Are you sure the XPath still matches the tag you want? – Jeff Hubbard Dec 26 '10 at 00:38
In all browsers it does. But not in my program. – Mathias Lykkegaard Lorenzen Dec 28 '10 at 13:04
As I said: Tag soup is not valid XML. Are you absolutely positive that your HTML-as-XML is translated the same way as you expect? I would dump the HTML-as-XML and check to make sure your XPath matches correctly still. – Jeff Hubbard Dec 28 '10 at 18:36

score 4 · Answer 2 · answered Dec 25 '10 at 23:36

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XPath has been supported in .NET since day 1. However, it only supports well-formed XML. Not all valid HTML is well-formed XML, and unclosed tags are not well-formed XML.

answered Dec 25 '10 at 23:36

John Saunders

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score 2 · Answer 3 · answered Dec 25 '10 at 23:29

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Yes. See System.Xml.XPath.XPathExpression. It lives in System.Xml.dll, which is included on any machine that has the .NET Framework installed.

Not sure about the unclosed HTML tags question. A small experiment should answer that pretty quickly.

answered Dec 25 '10 at 23:29

dthorpe

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The answer to unclosed tags is "no". – John Saunders Dec 25 '10 at 23:34

XPath to parse invalid HTML in .NET 4.0?

3 Answers3