Variable arg function question

[Roland Smith]

On Sun, May 04, 2008 at 04:01:39AM -0700, Unga wrote:
> > > Unfortunately va_arg() [stdarg(3)] does not return
> > > NULL or any other suitable value after processing
> > the
> > > arg list, it just simply crashes once the arg list
> > is
> > > exhausted.
> > 
> > It is _your_ task to properly close the argument
> > list. E.g. by supplying
> > a NULL pointer as the last argument.
> >  
> Infact, I have implemented it in this way. I was
> wondering if there is a better way.

Not really within the bounds of the C language.

> > > How do you guys implement variable arg function
> > such
> > > as f(str1, str2, str3, ..., strN)?
> > 
> > you could use the same format as main: int foo(int
> > num, char **args)
> > 
> 
> This is interesting. Who set the num? The compiler or
> the user. If it is the user, its no better than above
> NULL pointer method.
> 
> If this is possible, my problem is solved:
> f(str1, str2, str3, ..., strN) is at compile time
> expands to _f(int num, str1, str2, str3, ..., strN).
> 
> The num is set automatically by the compiler by
> counting the args.
> 
> Is this possible?

You could write a custom preporcessor that translates f calls into calls
for _f.

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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