vc中xml处理问题！

[smartlife]

int CXmlManage::GetIndexByNode(void* NodePtr)
{
IXMLDOMElementPtr NewNodePtr =(IXMLDOMElementPtr) NodePtr;
}

像这样的强制造型 报错

error C2227: left of '->QueryInterface' must point to class/struct/union
c:\program files\microsoft visual studio\vc98\include\comip.h(75) : see reference to function template instantiation 'long __thiscall _com_ptr_t<class _com_IIID<struct MSXML::IXMLDOMElement,&struct __s_GUID _GUID_2933bf86_7b36_11d2_b20e_00c
04f983e60> >::_QueryInterface(void *const & )' being compiled

为什么？？？

[smartlife]

上面那句改成这样即可！
IXMLDOMElementPtr NewNodePtr = (IXMLDOMElement *) NodePtr;

那位给说说原因！