[개발/MFC] VARIANT, BSTR, SAFEARRAY C++ Tutorial

출처 :  http://msdn.microsoft.com/en-us/library/e305240e-9e11-4006-98cc-26f4932d2118(VS.85) 

VARIANT, BSTR & SAFEARRAY C++ Tutorial... Introduction Frustrated by the lack of good articles on the VARIANT data type, I decided to write this short introduction. The VARIANT type is an all purpose data type used by IDispatch::Invoke both to transmit and receive parameters. It can hold numbers, strings, arrays, error values and IDispatch pointers. An XLL developer could consider the variant to be the Automation equivalent of the do everything Excel XLOPER data type. Structure Here is a simplified version of the VARIANT definition. For the full definition see this link. struct tagVARIANT {     VARTYPE vt; // unsigned short integer type code     WORD wReserved1;     WORD wReserved2;     WORD wReserved3;     union {     //  C++ Type      Union Name   Type Tag                Basic Type     //  --------      ----------   --------                ----------         long          lVal;        // VT_I4                ByVal Long         unsigned char bVal;        // VT_UI1               ByVal Byte         short         iVal;        // VT_I2                ByVal Integer         double        dblVal;      // VT_R8                ByVal Double         VARIANT_BOOL  boolVal;     // VT_BOOL              ByVal Boolean         SCODE         scode;       // VT_ERROR         DATE          date;        // VT_DATE              ByVal Date         BSTR          bstrVal;     // VT_BSTR              ByVal String         IUnknown      *punkVal;    // VT_UNKNOWN          IDispatch     *pdispVal;   // VT_DISPATCH          ByVal Object         SAFEARRAY     *parray;     // VT_ARRAY|*           ByVal array         // A bunch of other types that don't matter here...         VARIANT       *pvarVal;    // VT_BYREF|VT_VARIANT  ByRef Variant         void          * byref;     // Generic ByRef             }; }; The variant type is 16 bytes in size. [출처] variant|작성자 najira00