Re: recompile a DLL with _stdcall for VB

From:
"Alex Blekhman" <tkfx.REMOVE@yahoo.com>
Newsgroups:
microsoft.public.vc.language
Date:
Mon, 19 Nov 2007 14:13:46 +0200
Message-ID:
<eOcgkWqKIHA.536@TK2MSFTNGP06.phx.gbl>
<pink0.pallino@libero.it> wrote:

`CALLBACK' is defined as `__stdcall' in WinDef.h header.

Alex- Hide quoted text -

- Show quoted text -


thnk you for the replay.
well, this is the error I get when I try to compile the
dll:
error C2059: syntax error : '__stdcall'

the functions are so written:

BOOL STDDLLEXPORT myfunctionSTD(int nvalue, void
(CALLBACK*
amIReadyCallback)(int, LPVOID), LPVOID lpvParameter)
{ //function wrapper for VB
BOOL value;
value= myfunctionCDECL( nvalue,(CALLBACK*
amIReadyCallback)(int,
LPVOID), lpvParameter); <---here I get the error
return value;
}


You get the error because you supplies type info along the
parameter. You don't need it:

BOOL STDDLLEXPORT myfunctionSTD(
    int nvalue,
    void (CALLBACK* amIReadyCallback)(int, LPVOID),
    LPVOID lpvParameter
)
{ //function wrapper for VB
    BOOL value = myfunctionCDECL(
        nvalue, amIReadyCallback, lpvParameter);

    return value;
}

Tt will be much easier for you if you use typedef to reduce
syntax clutter:

typedef void (CALLBACK* MYFUNC)(int, LPVOID);

BOOL STDDLLEXPORT myfunctionSTD(
    int nvalue,
    MYFUNC pFunc,
    LPVOID lpvParameter
)
{ //function wrapper for VB
    BOOL value = myfunctionCDECL(
        nvalue, pFunc, lpvParameter);

    return value;
}

so my questions are:
do I need to write a wrapper for the myFunctionCDECL ?
if yes, how do I call the callback function inside the
wrapper?


Yes, you need to write a wrapper. Here's description of how
to do it:

KB153586 - "How To Call C Functions That Use the _cdecl
Calling Convention"
http://support.microsoft.com/kb/153586

HTH
Alex

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