Problem with writing XML DOM tree to memory buffer.

From:

Stuart Redmann <DerTopper@web.de>

Newsgroups:

comp.os.ms-windows.programmer.win32,microsoft.public.vc.language

Date:

Wed, 04 Apr 2007 11:43:23 +0200

Message-ID:

<euvv7v$4kj$1@news.dtag.de>

Hello newsgroup,

I tried to write a small test application that creates an XML DOM tree and writes the contents
into a string buffer (saving to file works perfectly). Unfortunately, I seem to go wrong
at some point (the text displayed contains only question marks :(

Can anybody give me some suggestions?

This code works under Visual C++ 6.0 with MSXML 4.0 installed. If you have a different
version of MSXML, you'll have to replace the version number in the CreateInstance call
of soDocument accordingly to be able to compile this example.

#include <afx.h>
#include <afxwin.h>
#include <comip.h>
#include <comdef.h>
#include <msxml2.h>
#include <atlbase.h>
#include <atlconv.h>

_COM_SMARTPTR_TYPEDEF (IXMLDOMNode, __uuidof (IXMLDOMNode));
_COM_SMARTPTR_TYPEDEF (IXMLDOMDocument2, __uuidof (IXMLDOMDocument2));
_COM_SMARTPTR_TYPEDEF (IXMLDOMAttribute, __uuidof (IXMLDOMAttribute));
_COM_SMARTPTR_TYPEDEF (IXMLDOMElement, __uuidof (IXMLDOMElement));
_COM_SMARTPTR_TYPEDEF (IStream, __uuidof (IStream));

int main ()
{
   USES_CONVERSION;
   ::CoInitialize (NULL);
   {
     // Create the document and fill it with some example data.
     IXMLDOMDocument2Ptr spDocument;
     spDocument.CreateInstance(__uuidof(DOMDocument40));
     IXMLDOMElementPtr spCurrentNode;
     spDocument->createElement (CComBSTR (L"ExposureTime").Detach (), &spCurrentNode);
     spCurrentNode->setAttribute (CComBSTR (L"value").Detach (), CComVariant ((double)3.14159));
     IXMLDOMNodePtr spUnused;
     spDocument->appendChild (spCurrentNode, &spUnused);

     // Let the document persist into a memory stream.
     IStreamPtr spStream;
     HGLOBAL MemoryHandle = ::GlobalAlloc (GMEM_MOVEABLE, 3000);
     VERIFY (SUCCEEDED (::CreateStreamOnHGlobal (MemoryHandle, FALSE, (IStream**) &spStream)));
     VERIFY (SUCCEEDED (spDocument->save (CComVariant (spStream))));

     // I simply guessed, that the stream stores the text as UNICODE, but I also
     // tried this with ANSII characters.
     CString XMLText = OLE2CT ((const wchar_t*) ::GlobalLock (MemoryHandle));
     ::AfxMessageBox (XMLText);
   }
   ::CoUninitialize();
   return 0;
}

Thanks in advance,
Stuart