Source: saveDOM.cpp

This C/C++ source code performs the following steps:

1. Creates an XML DOM object (pXMLDom) and sets it to synchronous mode.

2. Loads an XML string to pXMLDom.

3. Calls the loadXML method on pXMLDom, specifying the XML data as the following string:

   <r>\n<t>top</t>\n<b>bottom</b>\n</r>
   

4. Displays the resulting XML DOM in the console window.

5. Calls the save method on pXMLDom to serialize the DOM content to a file (myData.xml).

To add saveDOM.cpp to the project

1. Create a new C++ source file. For detailed instructions on how to do this, see Set Up My Visual C++ Project. Name the new file saveDOM.cpp.

2. Copy the C/C++ source code above and paste it into the source file you just created.

3. Next, build and run the saveDOM project. The result should be the output shown in the following topic.

C/C++ Source File (saveDOM.cpp)

// SaveDOM.cpp : Defines the entry point for the console application.
//

#include <stdio.h>
#include <tchar.h>
#include <msxml6.h>

// Macro that calls a COM method returning HRESULT value.
#define CHK_HR(stmt)        do{ hr=(stmt); if (FAILED(hr)) goto CleanUp; } while(0)

// Macro to verify memory allcation.
#define CHK_ALLOC(p)        do { if (!(p)) { hr = E_OUTOFMEMORY; goto CleanUp; } } while(0)

// Macro that releases a COM object if not NULL.
#define SAFE_RELEASE(p)     do { if ((p)) { (p)->Release(); (p) = NULL; } } while(0)

// Helper function to create a DOM instance. 
HRESULT CreateAndInitDOM(IXMLDOMDocument **ppDoc)
{
    HRESULT hr = CoCreateInstance(__uuidof(DOMDocument60), NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(ppDoc));
    if (SUCCEEDED(hr))
    {
        // these methods should not fail so don't inspect result
        (*ppDoc)->put_async(VARIANT_FALSE);  
        (*ppDoc)->put_validateOnParse(VARIANT_FALSE);
        (*ppDoc)->put_resolveExternals(VARIANT_FALSE);
    }
    return hr;
}

// Helper function to create a VT_BSTR variant from a null terminated string. 
HRESULT VariantFromString(PCWSTR wszValue, VARIANT &Variant)
{
    HRESULT hr = S_OK;
    BSTR bstrString = SysAllocString(wszValue);
    CHK_ALLOC(bstrString);

    V_VT(&Variant)   = VT_BSTR;
    V_BSTR(&Variant) = bstrString;

CleanUp:
    return hr;
}

void saveDOM()
{
    HRESULT hr = S_OK;
    IXMLDOMDocument *pXMLDom=NULL;
    IXMLDOMParseError *pXMLErr = NULL;
    BSTR bstrXML = NULL;
    BSTR bstrErr = NULL;
    VARIANT_BOOL varStatus;
    VARIANT varFileName;

    VariantInit(&varFileName);

    CHK_HR(CreateAndInitDOM(&pXMLDom));

    bstrXML = SysAllocString(L"<r>\n<t>top</t>\n<b>bottom</b>\n</r>");
    CHK_ALLOC(bstrXML);
    CHK_HR(pXMLDom->loadXML(bstrXML, &varStatus));

    if (varStatus == VARIANT_TRUE)
    {
        CHK_HR(pXMLDom->get_xml(&bstrXML));
        printf("XML DOM loaded from app:\n%S\n", bstrXML);

        VariantFromString(L"myData.xml", varFileName);
        CHK_HR(pXMLDom->save(varFileName));
        printf("XML DOM saved to myData.xml\n");
    }
    else
    {
        // Failed to load xml, get last parsing error
        CHK_HR(pXMLDom->get_parseError(&pXMLErr));
        CHK_HR(pXMLErr->get_reason(&bstrErr));
        printf("Failed to load DOM from xml string. %S\n", bstrErr);
    }

CleanUp:
    SAFE_RELEASE(pXMLDom);
    SAFE_RELEASE(pXMLErr);
    SysFreeString(bstrXML);
    SysFreeString(bstrErr);
    VariantClear(&varFileName);
}

int _tmain(int argc, _TCHAR* argv[])
{
    HRESULT hr = CoInitialize(NULL);
    if(SUCCEEDED(hr))
    {
        saveDOM();
        CoUninitialize();
    }

    return 0;

}