In article <392A9C47.CBAF0161@ipix.com>, tom.knapp@ipix.com says...

[ ... ]

> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
>
> I understand that the return value is of type "LRESULT".  What I am a
> bit puzzled about is the term "CALLBACK".  This line is compiled
> properly by MS Visual C++.  Is the inclusion of the "CALLBACK" term
> peculiar to the Visual C++ compiler, or is this standard C and/or C++?
> Microsoft documentation indicates that this term specifying the way the
> parameters are put on the stack.
>
> My basic question is this - is this standard C and/or C++ or is it
> specific to Microsoft?

It's sort-of Microsoft-specific.  Syntactically, it's more or less a
storage class specifier -- e.g. if it was preceded by:

#define CALLBACK extern
#define LRESULT long

then the code would be equivalent to:

long extern WndProc(/* ... */);

which is perfectly legal.  In this case, it happens that MS defines
some non-standard storage class specifiers of their own.  Depending
on your viewpoint, this might not really be a storage class specifier
at all though: I don't believe you're allowed to include more than
one storage class specifier for a single function, but I believe you
CAN legally have something like:

LRESULT CALLBACK extern WndProc(/* ... */);

so at the very least they're using a non-standard keyword, and what
they're doing probably doesn't even quite fit as legal C syntax
either.

--
    Later,
    Jerry.

The universe is a figment of its own imagination.

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I have a question regarding function declaration as used in MS Windows
programming.  An example is:

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);

I understand that the return value is of type "LRESULT".  What I am a
bit puzzled about is the term "CALLBACK".  This line is compiled
properly by MS Visual C++.  Is the inclusion of the "CALLBACK" term
peculiar to the Visual C++ compiler, or is this standard C and/or C++?
Microsoft documentation indicates that this term specifying the way the
parameters are put on the stack.

My basic question is this - is this standard C and/or C++ or is it
specific to Microsoft?

Thanks.

--
Best regards,

Thomas R. Knapp

***********************************************************************

"To understand is hard.  Once one understands, action is easy."
                          -- Sun Yat-sen, Chinese statesman (1866-1925)

***********************************************************************


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Thomas R. Knapp <tom.knapp@ipix.com> wrote in message
news:392A9C47.CBAF0161@ipix.com...
> I have a question regarding function declaration as used in MS Windows
> programming.  An example is:
>
> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
>
> I understand that the return value is of type "LRESULT".  What I am a
> bit puzzled about is the term "CALLBACK".  This line is compiled
> properly by MS Visual C++.  Is the inclusion of the "CALLBACK" term
> peculiar to the Visual C++ compiler, or is this standard C and/or C++?
> Microsoft documentation indicates that this term specifying the way the
> parameters are put on the stack.
>
> My basic question is this - is this standard C and/or C++ or is it
> specific to Microsoft?

Microsoft specific.

-Mike




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All declarations on the line:
     "LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);"
are specific to microsoft.  You will find all the UPPERCASE words to be
either typedefs or macros somewhere in the #include hierarchy.

"Thomas R. Knapp" wrote:
>
> I have a question regarding function declaration as used in MS Windows
> programming.  An example is:
>
> LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);
>
> I understand that the return value is of type "LRESULT".  What I am a
> bit puzzled about is the term "CALLBACK".  This line is compiled
> properly by MS Visual C++.  Is the inclusion of the "CALLBACK" term
> peculiar to the Visual C++ compiler, or is this standard C and/or C++?
> Microsoft documentation indicates that this term specifying the way the
> parameters are put on the stack.
>
> My basic question is this - is this standard C and/or C++ or is it
> specific to Microsoft?
>
> Thanks.
>
> --
> Best regards,
>
> Thomas R. Knapp
>
> ***********************************************************************
>
> "To understand is hard.  Once one understands, action is easy."
>                           -- Sun Yat-sen, Chinese statesman (1866-1925)
>
> ***********************************************************************
>
> ---
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