Try this, I found this years ago on the web.
#include <msxml2.h>
bool FormatDOMDocument (IXMLDOMDocument *pDoc, IStream *pStream)
{
// Create the writer
CComPtr <IMXWriter> pMXWriter;
if (FAILED (pMXWriter.CoCreateInstance(__uuidof (MXXMLWriter), NULL, CLSCTX_ALL)))
{
return false;
}
CComPtr <ISAXContentHandler> pISAXContentHandler;
if (FAILED (pMXWriter.QueryInterface(&pISAXContentHandler)))
{
return false;
}
CComPtr <ISAXErrorHandler> pISAXErrorHandler;
if (FAILED (pMXWriter.QueryInterface (&pISAXErrorHandler)))
{
return false;
}
CComPtr <ISAXDTDHandler> pISAXDTDHandler;
if (FAILED (pMXWriter.QueryInterface (&pISAXDTDHandler)))
{
return false;
}
if (FAILED (pMXWriter ->put_omitXMLDeclaration (VARIANT_FALSE)) ||
FAILED (pMXWriter ->put_standalone (VARIANT_TRUE)) ||
FAILED (pMXWriter ->put_indent (VARIANT_TRUE)) ||
FAILED (pMXWriter ->put_encoding (L"UTF-8")))
{
return false;
}
// Create the SAX reader
CComPtr <ISAXXMLReader> pSAXReader;
if (FAILED (pSAXReader.CoCreateInstance (__uuidof (SAXXMLReader), NULL, CLSCTX_ALL)))
{
return false;
}
if (FAILED (pSAXReader ->putContentHandler (pISAXContentHandler)) ||
FAILED (pSAXReader ->putDTDHandler (pISAXDTDHandler)) ||
FAILED (pSAXReader ->putErrorHandler (pISAXErrorHandler)) ||
FAILED (pSAXReader ->putProperty (
L"http://xml.org/sax/properties/lexical-handler", CComVariant (pMXWriter))) ||
FAILED (pSAXReader ->putProperty (
L"http://xml.org/sax/properties/declaration-handler", CComVariant (pMXWriter))))
{
return false;
}
// Perform the write
return
SUCCEEDED (pMXWriter ->put_output (CComVariant (pStream))) &&
SUCCEEDED (pSAXReader ->parse (CComVariant (pDoc)));
}