How to create excel pivot table from C++ (ole/com without mfc)

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C++

COM

MS-Excel

pivot-table

OLE

Dear experts,
Could anybody advise me how to create a pivot table in Excel using C++ (not using MFC or #import)? In particular, how Range should be defined to be properly passed into IDispatch::invoke(...) function on a stage of PivotCach object creation? In VB it looks like:

Dim aWrkBook As Workbook
Set aWrkBook = ActiveWorkbook

Dim pvtCaches As PivotCaches
Set pvtCaches = aWrkBook.PivotCaches

Dim pvtcache As PivotCache
Set pvtcache = pvtCaches.Create(xlDatabase, "ComponentsByAssy!R1C1:R2301C68", xlPivotTableVersion15)

Dim pvtTable As PivotTable
Set pvtTable = pvtcache.CreatePivotTable("TOTAL!R1C1", "PivotTable1", xlPivotTableVersion15)

Note: I especially divided operations for better visibility and comparison with C++ code.

In my interfaceMsExcel C++ class the function for Pivot Table creation currently looks as follows:

void interfaceMsExcel::createPivotTable(char *sourceDatasheetName,
                                        char *sourceCellsRange,
                                        char *destDatasheetName,
                                        char *destCellsRange,
                                        char *pivotTableName)
{
  if (pXlApp == NULL) return;

  // Get ActiveWorkbook:
  VARIANT result;
  VariantInit(&result);
  AutoWrap(DISPATCH_PROPERTYGET, &result, pXlApp, L"ActiveWorkbook", 0);
  if ((pXlActiveWorkbook = result.pdispVal) == 0)
  {// output error message:
   fl_alert("Cannot get ActiveWorkbook");
   return;
  }
  // Get PivotCaches object:
  VariantInit(&result);
  AutoWrap(DISPATCH_METHOD, &result, pXlActiveWorkbook, L"PivotCaches", 0);
  if ((pXlPivotCaches = result.pdispVal) == 0)
  {// output error message:
    fl_alert("Cannot get PivotCaches");
    return;
  }

  VARIANT sourceType, version;
  VariantInit ( & sourceType);
  sourceType.vt = VT_I4;
  sourceType.intVal = xlDatabase; // = 1

  VariantInit ( & version);
  version.vt = VT_I4;
  version.intVal = xlPivotTableVersion15; // = 5

  VARIANT sourceRange;
  VariantInit ( & sourceRange);
  // if it is defined as below:
  // sourceRange.vt = VT_BSTR;
  // sourceRange.bstrVal = L"ComponentsByAssy!A1:H100"
  // I receive error: "Parameter cannot be coerced";
  // If I use the following instead:
  sourceRange.vt = VT_DISPATCH;
  sourceRange.pdispVal = pXlRange;
  //I receive error "The application raised an Exception"
  VariantInit(&result);
  // Create PivotCach object:
  AutoWrap(DISPATCH_METHOD, &result, pXlPivotCaches, L"Create", 3, sourceType, sourceRange, version);
  if ((pXlPivotCache = result.pdispVal) == 0)
  { // Error message:
    fl_alert("Cannot create PivotCache");
    return;
  }
  // ...
  // Create PivotTable object:
  // ...
}

Some variables undeclared in the function defined as class members, for example pXlRange defined earlier and used in another functions with success):

class interfaceMsExcel
{
  private: // variables:
    VARIANT arr;
    IDispatch *pXlApp;
    IDispatch *pXlWindow;
    IDispatch *pXlBooks;
    IDispatch *pXlBook;
    IDispatch *pXlActiveWorkbook;
    IDispatch *pActiveSheet;
    IDispatch *pXlSheet;
    IDispatch *pXlSheets;
    IDispatch *pXlRange;
    IDispatch *pXlColumns;
    ...
    IDispatch *pXlPivotCaches; // Pivot Table Cache;
    IDispatch *pXlPivotCache;
  public:
    //...
    void createPivotTable(char *sourceDatasheetName, char *sourceCellsRange, char *destDatasheetName, char *destCellsRange, char *pivotTableName);
    //...
}

What I have tried:

I created my own wrapper class taking into account MSDN article "How to automate Excel from C++ without using MFC or #import". I can successfully transfer large amount of data to Excel with formatting.
Now I need to create a Pivot Table in the same Workbook. And I have a problem. I know that parameter containing Range shall be defined as VARIANT and I do not know in details how to define it so it could be properly recognized by excel interface. I tried to set the parameter as VT_BSTR type and receive error: "Parameter cannot be coerced"; when I try to set parameter with VT_DISPATCH type I receive error: "The application raised an Exception".
In MSDN this parameter for VB described as Range object. How properly define it in C++?

Thank you in advance for your time.