IsAvailable Example for C++ 5.0 and later

ILEADRasterTwain_U * pRasterTwain;

HRESULT hr = ::CoCreateInstance(CLSID_LEADRasterTwain_U, NULL, CLSCTX_ALL, IID_ILEADRasterTwain_U, (void **)&pRasterTwain);
if (FAILED(hr) || !pRasterTwain)
{
	::MessageBox (NULL, _TEXT("Failed to create a Raster Twain Object"), _TEXT("Error"), MB_OK);
	return;
}

BOOL bRet; 

bRet = pRasterTwain->IsAvailable ((long)GetSafeHwnd());
if (bRet) 
	MessageBox(TEXT("Twain is installed"));
else
	MessageBox(TEXT("Twain is not installed"));