Processing HTML document with C#

Question

I have a few hundred static HTML files that need to be processed.

They contain links like this

 <a href="http://www.mysite.com/"&gt;Link&lt;/a&gt;

I need to add ?ref=self to any url that begins with http://www.mysite.com and becomes

<a href="http://www.mysite.com/?ref=self"&gt;Link&lt;/a&gt;

however, I do not know whether it's going to be http://www.mysite.com or http://www.mysite.com/ also it could be linked to a sub directory.

What's the most efficient way to do this? in C#

Answer 1

Parsing HTML can be tricky as HTML often contains poorly formed tags and attributes. I suggest looking into an existing HTML parsing library to do your heavy lifting, or, using XSLT to transform valid (x)HTML to your desired output.

This question http://stackoverflow.com/questions/56107/what-is-the-best-way-to-parse-html-in-c has some good links to HTML parsing libraries for C#.

Answer 2

What's the most efficient way to do this? in C#

1. Look for the string http://www.mysite.com.
2. If it doesn't exist, go to 7.
3. Look for the next ".
4. If it doesn't exist, error.
5. Insert ?ref=self before the ".
6. Go to 1.
7. Return.

This can be accomplished with the following regular expression substitution:

s#http://www.mysite.com[^"]*#&?ref=self#g

A nicer (more expressive) way would be to use an HTML parser and XPath.

Answer 3

You could use Page.Request.UrlReferrer to detect where the request came from.