Michael

If you're trying to translate a union struct, your best bet is to use a
variant there. In C, a variant is actually defined as a union.

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Please post/reply to the newsgroup(s) so
that everyone can benefit from the discussion.

Regards,

Klaus H. Probst, MCP

       ICQ: 22454937
      The VB Box: http://members.xoom.com/kprobst/
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Michael

struct  tagVARIANT
    {
    union
        {
        struct  __tagVARIANT
            {
            VARTYPE vt;
            WORD wReserved1;
            WORD wReserved2;
            WORD wReserved3;
            union
                {
                LONG lVal;
                BYTE bVal;
                SHORT iVal;
                FLOAT fltVal;
                DOUBLE dblVal;
                VARIANT_BOOL boolVal;
                _VARIANT_BOOL bool;
                SCODE scode;
                CY cyVal;
                DATE date;
                BSTR bstrVal;
                IUnknown __RPC_FAR *punkVal;
                IDispatch __RPC_FAR *pdispVal;
                SAFEARRAY __RPC_FAR *parray;
                BYTE __RPC_FAR *pbVal;
                SHORT __RPC_FAR *piVal;
                LONG __RPC_FAR *plVal;
                FLOAT __RPC_FAR *pfltVal;
                DOUBLE __RPC_FAR *pdblVal;
                VARIANT_BOOL __RPC_FAR *pboolVal;
                _VARIANT_BOOL __RPC_FAR *pbool;
                SCODE __RPC_FAR *pscode;
                CY __RPC_FAR *pcyVal;
                DATE __RPC_FAR *pdate;
                BSTR __RPC_FAR *pbstrVal;
                IUnknown __RPC_FAR *__RPC_FAR *ppunkVal;
                IDispatch __RPC_FAR *__RPC_FAR *ppdispVal;
                SAFEARRAY __RPC_FAR *__RPC_FAR *pparray;
                VARIANT __RPC_FAR *pvarVal;
                PVOID byref;
                CHAR cVal;
                USHORT uiVal;
                ULONG ulVal;
                INT intVal;
                UINT uintVal;
                DECIMAL __RPC_FAR *pdecVal;
                CHAR __RPC_FAR *pcVal;
                USHORT __RPC_FAR *puiVal;
                ULONG __RPC_FAR *pulVal;
                INT __RPC_FAR *pintVal;
                UINT __RPC_FAR *puintVal;
                struct  __tagBRECORD
                    {
                    PVOID pvRecord;
                    IRecordInfo __RPC_FAR *pRecInfo;
                    }   __VARIANT_NAME_4;
                }       __VARIANT_NAME_3;
            }   __VARIANT_NAME_2;
        DECIMAL decVal;
        }       __VARIANT_NAME_1;
    };

Looks like a union to me. Perhaps I didn't make myself very clear to the
original post. If an external API call requires the address of a union (or
a pointer to a union), then no, using a variant will probably not work.
But in a translation from C to VB, using a variant where a union was
expected will simplify coding the same way a union simplifies (some)
coding in C.

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Please post/reply to the newsgroup(s) so
that everyone can benefit from the discussion.

Regards,

Klaus H. Probst, MCP

       ICQ: 22454937
      The VB Box: http://members.xoom.com/kprobst/
~~~~~~~~~~~~~~~~~~~~~~~~~~~

which g is C language's  union type

When i call this function, as follow:
s(1,1)
second parameter  is not been passed as value 1.
Why ??

            {
            VARTYPE vt;
            WORD wReserved1;
            WORD wReserved2;
            WORD wReserved3;

before it ever gets to the Union. So using a variant here
will always fail in a struct that expects a Union with no
additional padding.

The point of converting VB structs to C structs is to make
sure the C code *thinks* that the data looks right. It will
never look right in this case if you use a Variant.

Michael

Michael