Variable arg function question

Roland Smith rsmith at
Sun May 4 07:55:21 UTC 2008

On Sun, May 04, 2008 at 12:40:43AM -0700, Unga wrote:
> Hi all
> I need to implement a variable argument function in C.
> The number of args are not known but the type is
> known, all are strings.
> 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.
> It seems there is no way to know the number of args
> inside the called function.

Not with stdarg.

> 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)

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