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Normally, in C++ one doesn't use void in a function declaration when it
takes no parameters. You need to in C. So what about a C++ function declared
with an extern "C"? Example:

extern "C" void __declspec(dllexport) functionName() // does this need to be
(void)?


As is probably evident, this is in a Windows DLL. Right now, the entire
program is C++. I don't know if it will ever be used with C modules.



Brian

* Default User, on 14.03.2011 01:23:
> Normally, in C++ one doesn't use void in a function declaration when it
> takes no parameters. You need to in C. So what about a C++ function declared
> with an extern "C"? Example:
>
> extern "C" void __declspec(dllexport) functionName() // does this need to be
> (void)?
>
>
> As is probably evident, this is in a Windows DLL. Right now, the entire
> program is C++. I don't know if it will ever be used with C modules.

In C the 'void' formal argument list tells the C compiler that this function
does not accept any arguments.

But the C linkage link level name doesn't tell this: by convention it doesn't
depend on the function signature.

And so if the above had truly produced a C convention link level name, then a
"void" would not serve any purpose, since it's not seen by the C compiler, and
since with true C link level names it would not affect the link level name.

However, the above is Microsoft stuff.

With Microsoft's conventions "extern C" does not necessarily produce C
convention link level names. And so the answer is platform- and compiler-
specific. I do not know that answer, but you can use a tool such as Microsoft's
"dumpbin" to check the link-level names, or, ask in a Microsoft group (it's
off-topic here since this group deals only with standard C++).


Cheers & hth.,

- Alf

--
blog at <url: http://alfps.wordpress.com>

"Default User" <>
> Normally, in C++ one doesn't use void in a function declaration when it
> takes no parameters. You need to in C. So what about a C++ function
> declared with an extern "C"? Example:
>
> extern "C" void __declspec(dllexport) functionName() // does this need to
> be (void)?

If you do it this way, no. As a C compiler could not compile it anyway.

If you have the regular layout for double-compile, where the extern "C" part
is present with __cplusplus, then you need void for the C build to avoid
those "not a prototype" warnings.

"Alf P. Steinbach /Usenet" <alf.p.steinbach+> wrote in
message news:ilk04o$82l$...
>* Default User, on 14.03.2011 01:23:
>> Normally, in C++ one doesn't use void in a function declaration when it
>> takes no parameters. You need to in C. So what about a C++ function
>> declared
>> with an extern "C"? Example:
>>
>> extern "C" void __declspec(dllexport) functionName() // does this need to
>> be
>> (void)?
>>
>>
>> As is probably evident, this is in a Windows DLL. Right now, the entire
>> program is C++. I don't know if it will ever be used with C modules.
>
> In C the 'void' formal argument list tells the C compiler that this
> function does not accept any arguments.
>
> But the C linkage link level name doesn't tell this: by convention it
> doesn't depend on the function signature.
>
> And so if the above had truly produced a C convention link level name,
> then a "void" would not serve any purpose, since it's not seen by the C
> compiler, and since with true C link level names it would not affect the
> link level name.

That's what I thought, thanks.



Brian