printf() problem

[Henry Spencer]

In article <1367 at ndmath.UUCP> dierks at ndmath.UUCP (Tim Dierks) writes:
>  I understand that the _order_ of evaluation is undefined...  My question
>is if the stack-based method of passing arguments, or the order in which
>the arguments are passed, is part of the C definition.  The alternative
>seems to me to be making all functions that take a variable number of
>arguments non-portable.  Is this the case?

No definition of C mandates a stack, or any ordering of arguments within
anything.  Variadic functions need to use non-portable machinery to pick
up their arguments, although modern practice is to encapsulate said
machinery inside macros with portable interfaces, like <varargs.h> or
<stdarg.h>.

Stacks are actually usually a bad way of passing arguments.  Passing at
least the first two or three parameters in registers is often superior.
(Although it complicates <varargs.h> etc., and can break crufty old
programs.)
-- 
Mars in 1980s:  USSR, 2 tries, |     Henry Spencer at U of Toronto Zoology
2 failures; USA, 0 tries.      | uunet!attcan!utzoo!henry henry at zoo.toronto.edu