Question

What are analogues for Delphi types TVarType and OleVariant in C/C++ ?

Answer 1

Well, clearly from their own documentation – the first is simply an unsigned word – a uint_16.

The second is a little more difficult to explain. It’s basically a great big struct that contains a whole bunch of fields. This one data type includes a field for each data-type that could be transferred to/from a COM object. This means you just need to concern yourself with passing a variant to/from the object. It’s then up to each of you (programmer/COM object) to extract/insert data at the relevant places.

Perhaps I shouldn’t, but here’s the definition for a VARIANT from oaidl.h (gcc, win32)

typedef struct tagVARIANT {
  _ANONYMOUS_UNION union {
    struct __tagVARIANT {
    VARTYPE vt;
    WORD wReserved1;
    WORD wReserved2;
    WORD wReserved3;
    _ANONYMOUS_UNION union {
        long lVal;
        LONGLONG llVal;
        unsigned char bVal;
        short iVal;
        float fltVal;
        double dblVal;
        VARIANT_BOOL  boolVal;
        SCODE scode;
        CY cyVal;
        DATE date;
        BSTR bstrVal;
        IUnknown *punkVal;
        LPDISPATCH pdispVal;
        SAFEARRAY *parray;
        unsigned char *pbVal;
        short *piVal;
        long *plVal;
        LONGLONG  * pllVal;
        float *pfltVal;
        double *pdblVal;
        VARIANT_BOOL *pboolVal;
        _VARIANT_BOOL  *pbool;
        SCODE *pscode;
        CY *pcyVal;
        DATE *pdate;
        BSTR *pbstrVal;
        IUnknown **ppunkVal;
        LPDISPATCH *ppdispVal;
        SAFEARRAY **pparray;
        struct tagVARIANT *pvarVal;
        void *byref;
        CHAR cVal;
        USHORT uiVal;
        ULONG ulVal;
        ULONGLONG ullVal;
        INT intVal;
        UINT uintVal;
        DECIMAL *pdecVal;
        CHAR  *pcVal;
        USHORT  *puiVal;
        ULONG  *pulVal;
        ULONGLONG * pullVal;
        INT  *pintVal;
        UINT  *puintVal;
        _ANONYMOUS_STRUCT struct {
            PVOID pvRecord;
            struct IRecordInfo *pRecInfo;
        } __VARIANT_NAME_4;
    } __VARIANT_NAME_3;
    } __VARIANT_NAME_2;
    DECIMAL decVal;
  } __VARIANT_NAME_1;
} VARIANT,*LPVARIANT;