其实你已经知道方法了
msdn中有该类数据的介绍:(下面就是录自MSDN)
VARIANT and VARIANTARG
Use VARIANTARG to describe arguments passed within DISPPARAMS, and VARIANT to specify variant data that cannot be passed by reference. The VARIANT type cannot have the VT_BYREF bit set. VARIANTs can be passed by value, even if VARIANTARGs cannot.