Question

I have a program where it reads and writes XML using XMLReader and XMLWriter

 XmlWriter writer =
 XmlWriter.Create(fullpath, settings);

 //content...

 writer.Flush();

 writer.Close();

and my reader code

XmlReader reader = XmlReader.Create(fullpath);

while (reader.Read())
        {
            switch(reader.NodeType)
            {
                case XmlNodeType.Element:
                    Console.WriteLine("Element: " + reader.Name);

                    while(reader.MoveToNextAttribute())
                    {

                        Console.WriteLine("\tAttribute: [" + reader.Name + "] = '" + 
                        reader.Value + "'");
                    }
                    break;

                case XmlNodeType.DocumentType: 
                    Console.WriteLine("Document: " + reader.Value); 
                    break;

                case XmlNodeType.Comment:
                    Console.WriteLine("comment: " + reader.Value);
                    break;

                default: 
                    Console.WriteLine("unknown type, error!");
                    break;
            }
        }

        reader.Close()

The writer works fine, but when it gets to XmlReader reader = XmlReader.Create(fullpath);

it prints the unknown type error message twice and crashes with the error

Unhandled Exception:
System.Xml.XmlException: For security
reasons DTD is prohib
ited in this XML document. To enable DTD processing set the
ProhibitDtd property
on XmlReaderSettings to false and pass the settings into
XmlReader.Create metho
d.
at System.Xml.XmlTextReaderImpl.Throw(Exception
e)
at System.Xml.XmlTextReaderImpl.ThrowWithoutLineInfo(String
res, String arg)
at System.Xml.XmlTextReaderImpl.ParseDoctypeDecl()
at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
at System.Xml.XmlTextReaderImpl.Read()
at writefile.Main() in C:\Main\C#June\CH9\CodeFile1.cs:line

I tried adding this before XmlReader.Create(fullpath)

XmlReaderSettings settingsread = new XmlReaderSettings();
settingsread.ProhibitDtd = false;

I still get the same error, what’s the real problem in this program?

Answer 1

I believe you would need to change your reader create to reference the settings

XmlReader reader = XmlReader.Create(fullpath);

should become

XmlReader reader = XmlReader.Create(fullpath, settingsread);