Marshalling Variant Arrays from COM

[Andrew S. Giles]

Helo all,

I have a standalone unmanaged C++ application that makes a call on another
standalone COM server, which raises an event that should be handled in C#.

I am trying to send: unsigned long, double, BSTR, and VARIANT.

The unsigned long, double, and BSTR (marshalled to System.String) work just
fine and dandy.

Now we get to the variants.

I build a SAFEARRAY in C++, and assign first doubles, the fire the COM call;
then integers, fire the COM call, then BSTR, and fire the COM call.

Only the integers make it to the C# event handler.

I am using 1 method to handle ANY variant. I tried 3 different methods, one
each for VARIANTs containing an array of doubles, array of unsigned longs and
array of BSTR. Only the Integer array made it through.

I also changed my code, so instead of assigning VARIANT.vt = R8 | VT_ARRAY
(or VT_BSTR | VT_ARRAY) I used VT_I4 | VT_ARRAY and it made it across all
three times.

Can anyone enlighten me as to just what is going on? It seems like the C#
compiler or processor is checking the underlying TYPES in the VARIANT, and
only allowing over VT_I4 types.

Am I assigning the VARIANT.vt field wrong in C++?

Thanks in advance,

Andrew S. Giles