How to read HTML as XML?

I want to extract a couple of links from an html page downloaded from the internet, I think that using linq to XML would be a good solution for my case.

My problem is that I can't create an XmlDocument from the HTML, using Load(string url) didn't work so I downloaded the html to a string using:

public static string readHTML(string url)
    {
        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
        HttpWebResponse res = (HttpWebResponse)req.GetResponse();
        StreamReade开发者_如何学编程r sr = new StreamReader(res.GetResponseStream());

        string html = sr.ReadToEnd();
        sr.Close();
        return html;
    }

When I try to load that string using LoadXml(string xml) I get the exception

'--' is an unexpected token. The expected token is '>'

What way should I take to read the html file to a parsable XML

HTML simply isn’t the same as XML (unless the HTML actually happens to be conforming XHTML or HTML5 in XML mode). The best way is to use a HTML parser to read the HTML. Afterwards you may transform it to Linq to XML – or process it directly.

I haven't used it myself, but I suggest you take a look at SgmlReader. Here's a sample from their home page:

// setup SgmlReader
Sgml.SgmlReader sgmlReader = new Sgml.SgmlReader()
{
    DocType = "HTML",
    WhitespaceHandling = WhitespaceHandling.All,
    CaseFolding = Sgml.CaseFolding.ToLower,
    InputStream = reader
};

// create document
XmlDocument doc = new XmlDocument()
{
    PreserveWhitespace = true,
    XmlResolver = null
};
doc.Load(sgmlReader);
return doc;

If you want to extract some links from a page, as you mentioned, try using HTML Agility Pack.

This code gets a page from the web and extracts all links:

HtmlWeb web = new HtmlWeb();  
HtmlDocument document = web.Load("http://www.stackoverflow.com");  
HtmlNode[] links = document.DocumentNode.SelectNodes("//a").ToArray(); 

Open an html file from disk and get URL for specific link:

HtmlDocument document2 = new HtmlDocument();  
document2.Load(@"C:\Temp\page.html")  
HtmlNode link = document2.DocumentNode.SelectSingleNode("//a[@id='myLink']");
Console.WriteLine(link.Attributes["href"].Value);

HTML is not XML. HTML is based on SGML, and as such does not ensure that the markup is well-formed XML (XML is a subset of SGML itself). You can only parse XHTML, i.e. XML compatible HTML, as XML. But of course that is not the case for most of the websites.

To work with HTML, you need to use a HTML parser.

If you know the nodes you're interested in I would use regex to extract the links from the string.