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Asked: 2026-05-18T00:48:05+00:00

In .NET/C#, I want to validate some html code. For instance I have the

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In .NET/C#, I want to validate some html code. For instance I have the following HTML :

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
  <head><title></title></head>
  <body>
   CDATA section number 1?
  </body>
</html>

I have the following C# code:

string htmlCode = ... // for instance the html above
var settings = new XmlReaderSettings { ValidationType = ValidationType.DTD };
settings.ValidationEventHandler += delegate(object s, ValidationEventArgs e)
{
    throw new XmlException(e.Message);
};
using (var srdr = new StringReader(htmlCode))
using (var xrdr = new XmlTextReader(srdr))
using (var vrdr = XmlReader.Create(xrdr, settings))
{
    try
    {
        while (vrdr.Read()) { }
    }
    catch (XmlException ex)
    {
        // do some stuff
    }
}

when I run this code I have this exception:

System.Net.WebException : The remote server returned an error: (403) Forbidden.
at System.Net.HttpWebRequest.GetResponse()

What’s wrong in what I’ve done? Thanks in advance for your help

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1 Answer

  1. Editorial Team

    It’s not your code.

    http://www.w3.org/blog/systeam/2008/02/08/w3c_s_excessive_dtd_traffic

    You need to supply the DTD yourself, for instance by using a custom XmlResolver which returns the DTD from a local resource.

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