How to define a struct data interface in a ActiveX control?

I hope define a struct interface as GetPostInfo(PostInfo* postinfo); in a ActiveX control,

for example this struct as following:
typedef Struct PostInfo
{
   long nIndex;
   BSTR strPostName;
} PostInfo
 
and how to define that parameter of a FUNCTION definition in a xxxctrl.h
DISP_FUNCTION(CxxxCtrl, "GetPostInfo", GetPostInfo, VT_BOOL, ?)

so I must define this PostInfo struct in ODL file, and I hope this interface as a common data type, for example DRAWITEMSTRUCT, the data can be transfer from COM inside to user.
GempinAsked:
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GempinAuthor Commented:
Experts, help me, please~~
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GempinAuthor Commented:
Experts, help me, please~~
0
boonshaCommented:
We are allowed to declare C and C++ style structures in an IDL file. Once declared they can be used like usual data types. This is show in the following IDL code.

         // declare structure

        typedef struct
        {
            double x ;
            double y ;
        } Point2d ;
       // interface IZ
       [object,uuid (32bb8325-b41b. 11cf-a6bb- 0080c7b2d682);
      helpstring ("IZInterface")
      pointer_default(unique)]
      interface IZ ; IUnknown
      {
                HRESULT StructIn ( [in] Point2d pt ) ;
                HRESULT StructOut ( [out] Point2d *pt ) ;
      } ;

As shown here the StructIn( ) method receives a structure of type Point2d and the method StructOut( ) returns a Point2d structure. Once the structure has been defined in the IDL file there is no need to declare it again in the client program. The client program can easily pass and receive this structure without the declaration. This is possible because when we #import the server’s type library file the structure declaration also gets imported.

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