Dim staad As Object
Dim stdfile As String
Set staad = GetObject(, "StaadPro.OpenSTAAD")
staad.GetSTAADFile stdfile, "TRUE"
Length = staad.geometry.getbeamlength(...)
Cells(2, 17).Value = Length
Next i

 	CoInitialize(NULL); 

 		
  CLSID clsApp; //The CLSID of Your app
  VARIANT App = {0}; //Variant who's contain the app
  IUnknown* punk; 
	if (FAILED(CoCreateInstance(clsApp, NULL, CLSCTX_SERVER,  IID_IUnknown, (void FAR* FAR*)&punk)))
	{
		MessageBox(NULL, "this App's not registered properly", "Error", 0x10010);
		throw OleException(14,"CoCreateInstance() => this App's ("+ appName.ToString()  +")not registered properly",1);
	}
  punk->QueryInterface(IID_IDispatch, (void **)&App.pdispVal); 

VARIANT buffer={0};
AutoWrap(DISPATCH_PROPERTYGET, &buffer, App.pdispVal, L"geometry", 0); //here we ask ole to retrieve geometry property of the object stored in APP and we put this "geometry property into VARIANT //buffer 
AutoWrap(DISPATCH_PROPERTYGET, &buffer, buffer.pdispVal, L"getbeamlength", 0); // here we ask ole to retrieve getbeamlength property of the object, the result is stored into buffer.
 // according to your code lenght seems to be integer so the result you asked with getbeamlength must be stored into buffer.intVal
int lenght = buffer.intVal

HRESULT AutoWrap(int autoType, VARIANT *pvResult, IDispatch *pDisp, LPOLESTR ptName, int cArgs...) {
// Begin variable-argument list...
va_list marker;
va_start(marker, cArgs);

if(!pDisp) {
    MessageBox(NULL, "NULL IDispatch passed to AutoWrap()", "Error", 0x10010);
    _exit(0);
}

// Variables used...
DISPPARAMS dp = { NULL, NULL, 0, 0 };
DISPID dispidNamed = DISPID_PROPERTYPUT;
DISPID dispID;
HRESULT hr;
char buf[200];
char szName[200];


// Convert down to ANSI
WideCharToMultiByte(CP_ACP, 0, ptName, -1, szName, 256, NULL, NULL);

// Get DISPID for name passed...
hr = pDisp->GetIDsOfNames(IID_NULL, &ptName, 1, LOCALE_USER_DEFAULT, &dispID);
if(FAILED(hr)) {
    sprintf(buf, "IDispatch::GetIDsOfNames(\"%s\") failed w/err 0x%08lx", szName, hr);
    MessageBox(NULL, buf, "AutoWrap()", 0x10010);
    _exit(0);
    return hr;
}

// Allocate memory for arguments...
VARIANT *pArgs = new VARIANT[cArgs+1];
// Extract arguments...
for(int i=0; i<cArgs; i++) {
    pArgs[i] = va_arg(marker, VARIANT);
}

// Build DISPPARAMS
dp.cArgs = cArgs;
dp.rgvarg = pArgs;

// Handle special-case for property-puts!
if(autoType & DISPATCH_PROPERTYPUT) {
    dp.cNamedArgs = 1;
    dp.rgdispidNamedArgs = &dispidNamed;
}

// Make the call!
hr = pDisp->Invoke(dispID, IID_NULL, LOCALE_SYSTEM_DEFAULT, autoType, &dp, pvResult, NULL, NULL);
if(FAILED(hr)) {
    sprintf(buf, "IDispatch::Invoke(\"%s\"=%08lx) failed w/err 0x%08lx", szName, dispID, hr);
    MessageBox(NULL, buf, "AutoWrap()", 0x10010);
    _exit(0);
    return hr;
}
// End variable-argument section...
va_end(marker);

delete [] pArgs;

return hr;
}

WideCharToMultiByte(CP_ACP, 0, ptName, -1, szName, 256, NULL, NULL);

CLSIDFromProgID(L"StaadPro.OpenSTAAD", &clsid);

HRESULT hr = GetActiveObject(clsid, NULL, (IUnknown**)&pUnk);

CLSID clsApp;
VARIANT App = {0};
IUnknown* punk;
HRESULT hr = CLSIDFromProgID(appName, &clsApp); 
if(!FAILED(hr)){
	HRESULT hr2 =GetActiveObject( clsApp, NULL, &punk );
	if (!FAILED(hr2)) {
	      hr2=punk->QueryInterface(IID_IDispatch, (void **)&App.pdispVal);
         }
}

//conversion BSTR to CHAR
//Don't forget #include <stdio.h>
Upp::String BSTRtoString (BSTR bstr)
{
    std::wstring ws(bstr);
    std::string str(ws.begin(), ws.end());
    return Upp::String(str);
}

Upp::String valueOfVariant =  BSTRtoString(myVariant.bstrVal);		

	StringBuffer stdfile;
	OleObject staad = OleAut::CreateObject("StaadPro.OpenSTAAD");
	staad.Method("GetSTAADFile", stdfile, true);

	int length = staad("geometry")("getbeamlength", x);