使用VARIANT来传递参数意味着非强类型语言(例如VBScript)能够调用使用强类型语言(C++)实现的方法。
VARIANT的结构可以参考头文件VC98IncludeOAIDL.H中关于结构体tagVARIANT的定义。
VARIANT 数据类型在文件OAIDL.IDL中定义如下：
- C/C++ code复制代码
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struct tagVARIANT { union { struct __tagVARIANT { VARTYPE vt; WORD wReserved1; WORD wReserved2; WORD wReserved3; union { ULONGLONG ullVal; /* VT_UI8 */ LONGLONG llVal; /* VT_I8 */ LONG lVal; /* VT_I4 */ BYTE bVal; /* VT_UI1 */ SHORT iVal; /* VT_I2 */ FLOAT fltVal; /* VT_R4 */ DOUBLE dblVal; /* VT_R8 */ VARIANT_BOOL boolVal; /* VT_BOOL */ _VARIANT_BOOL bool; /* (obsolete) */ SCODE scode; /* VT_ERROR */ CY cyVal; /* VT_CY */ DATE date; /* VT_DATE */ BSTR bstrVal; /* VT_BSTR */ IUnknown * punkVal; /* VT_UNKNOWN */ IDispatch * pdispVal; /* VT_DISPATCH */ SAFEARRAY * parray; /* VT_ARRAY */ BYTE * pbVal; /* VT_BYREF|VT_UI1 */ SHORT * piVal; /* VT_BYREF|VT_I2 */ LONG * plVal; /* VT_BYREF|VT_I4 */ LONGLONG * pllVal; /* VT_BYREF|VT_I8 */ FLOAT * pfltVal; /* VT_BYREF|VT_R4 */ DOUBLE * pdblVal; /* VT_BYREF|VT_R8 */ VARIANT_BOOL *pboolVal; /* VT_BYREF|VT_BOOL */ _VARIANT_BOOL *pbool; /* (obsolete) */ SCODE * pscode; /* VT_BYREF|VT_ERROR */ CY * pcyVal; /* VT_BYREF|VT_CY */ DATE * pdate; /* VT_BYREF|VT_DATE */ BSTR * pbstrVal; /* VT_BYREF|VT_BSTR */ IUnknown ** ppunkVal; /* VT_BYREF|VT_UNKNOWN */ IDispatch ** ppdispVal; /* VT_BYREF|VT_DISPATCH */ SAFEARRAY ** pparray; /* VT_BYREF|VT_ARRAY */ VARIANT * pvarVal; /* VT_BYREF|VT_VARIANT */ PVOID byref; /* Generic ByRef */ CHAR cVal; /* VT_I1 */ USHORT uiVal; /* VT_UI2 */ ULONG ulVal; /* VT_UI4 */ INT intVal; /* VT_INT */ UINT uintVal; /* VT_UINT */ DECIMAL * pdecVal; /* VT_BYREF|VT_DECIMAL */ CHAR * pcVal; /* VT_BYREF|VT_I1 */ USHORT * puiVal; /* VT_BYREF|VT_UI2 */ ULONG * pulVal; /* VT_BYREF|VT_UI4 */ ULONGLONG * pullVal; /* VT_BYREF|VT_UI8 */ INT * pintVal; /* VT_BYREF|VT_INT */ UINT * puintVal; /* VT_BYREF|VT_UINT */ struct __tagBRECORD { PVOID pvRecord; IRecordInfo * pRecInfo; } __VARIANT_NAME_4; /* VT_RECORD */ } __VARIANT_NAME_3; } __VARIANT_NAME_2; DECIMAL decVal; } __VARIANT_NAME_1; };
