Re: Recursion, Yo

On 11/04/2024 21:37, Keith Thompson wrote:

David Brown <david.brown@hesbynett.no> writes:

On 11/04/2024 02:18, Lawrence D'Oliveiro wrote:

On Wed, 10 Apr 2024 16:46:43 +0200, David Brown wrote:
>

Just for your entertainment, with C++ lambdas this is now legal code:
>
void foo(void) {
[](){}();
}

C programmer still has habit of writing “(void)” when C++ allows
“()”
instead.

>
I do that sometimes, yes.  I could argue that I think it is better to
be explicit than implicit, but it's just my fingers on automatic.  The
kinds of programs I work on can rarely be pure C++ - there's always
lots of C code too, and it's often useful to write code in a way that
is suitable for both C and C++.
>
In this particular case, of course, there's not much advantage to
having a C-style function declaration!
>

Does the latest C spec now also take “()” to mean “no args”
(synonymous
with “(void)”) instead of “unspecified args”?

>
It does, yes, in C23.  If you want to declare a function with no
information about the number or type of parameters, you can now write
"void foo(...);".  (Prior to C23 you needed at least one normal typed
parameter before the ellipsis.)

 That's not quite the same.  (...) declares a variadic function, whose
arguments (if any) can be accessed using the macros in <stdarg.h>.
Functions with an old-style () declaration can access their arguments by
names given in the definition Variadic functions could have a different
calling convention.
 

Good point.  Being able to write "T foo(...)" replaces any need to declare pre-C23 "T foo()", but it is not a direct replacement without changing code.  (It might work as a replacement in practice for simple cases, even though it is not required by the C standards - I don't know how compatible ellipsis arguments are with declared arguments.)
There should, hopefully, be very little code from the last generation that uses "T foo()" forms other than meaning "T foo(void)".