Creating XML without encoding attribute in prolog using XmlLite IXmlWriter (C++)

Question

I am using the XmlLite library to create an XML file. I want the resulting XML file's prolog to not include the encoding attribute (just the version):

<?xml version="1.0"?>

Here is my code:

    HRESULT hr = S_OK;
    IStream *pOutFileStream = NULL;
    IXmlWriter *pWriter = NULL;
    CComPtr<IXmlWriterOutput> pWriterOutput;

    //Open writeable output stream
    if (FAILED(hr = SHCreateStreamOnFile(output_file_name, STGM_CREATE | STGM_WRITE, &pOutFileStream)))
    {
        wprintf(L"Error creating file writer, error is %08.8lx", hr);
        HR(hr);
    }

    if (FAILED(hr = CreateXmlWriter(__uuidof(IXmlWriter), (void**) &pWriter, NULL)))
    {
        wprintf(L"Error creating xml writer, error is %08.8lx", hr);
        HR(hr);
    }

    if(FAILED(CreateXmlWriterOutputWithEncodingName(pOutFileStream, NULL, L"UTF-8", &pWriterOutput))){
        wprintf(L"Error setting xml encoding, error is %08.8lx", hr);
        HR(hr);
    }

    if (FAILED(hr = pWriter->SetOutput(pWriterOutput)))
    {
        wprintf(L"Error, Method: SetOutput, error is %08.8lx", hr);
        HR(hr);
    }

    if (FAILED(hr = pWriter->SetProperty(XmlWriterProperty_Indent, 4)))
    {
        wprintf(L"Error, Method: SetProperty XmlWriterProperty_Indent, error is %08.8lx", hr);
        HR(hr);
    }

    if (FAILED(hr = pWriter->WriteStartDocument(XmlStandalone_Omit)))
    {
        wprintf(L"Error, Method: WriteStartDocument, error is %08.8lx", hr);
        HR(hr);
    } 

I have tried removing the call to CreateXmlWriterOutputWithEncodingName() but even then a default encoding attribute with UTF-8 is getting created. I have also tried putting NULL as the third parameter to that function.

Assistance would be much appreciated!

Answer 1

The XML declaration is written by the WriteStartDocument method.

Instead of calling WriteStartDocument, you can call WriteProcessingInstruction with L"xml" as the name of the processing instruction to write the XML declaration the way you want, for example:

if (FAILED(hr = pWriter->WriteProcessingInstruction(L"xml", L"version=\"1.0\"")))
{
    wprintf(L"Error, Method: WriteProcessingInstruction, error is %08.8lx", hr); 
    HR(hr); 
}

This will write the XML declaration as <?xml version="1.0"?>.