🚀 go-pugleaf

In article <8s2apd$aqe$1@yin.interaccess.com>,
Kenny McCormack <gazelle@interaccess.com> wrote:
>The goal is not to solve any particular problem (other than the "find the
>maximum of a list of numbers" problem shown above), but rather to understand
>how the various implementations (of the variable args functionality) work.

Basically, K&R C had varargs.  The standardization committee designed
stdargs as the replacement for it.  The main difference has to do with the
fact that stdargs is designed to coexist with function prototypes, i.e. the
funcname(<fixed args>,...) notation.

>What I'd like to see is an implementation of the max() function that doesn't
>require a 0 to be passed to signal the end of the list (and, consequently,
>has the limitation that 0 can't be a valid data point).

Neither varargs nor stdargs provides a way to find out how many arguments
were passed.  If you don't want to pass a marker for the end of the list,
pass the number of arguments as the first argument, e.g.

max(5, 100, 0, -10, 150, 9)

This also solves the problem of requiring at least one fixed argument for
this function.

>But thanks for the note about vprintf - this seems to imply that there
>should be wrapper functions provided by the system for any "standard"
>functions that take variable numbers of args.  I note that there is a
>vscanf; are there any other standard functions that take variable numbers of
>args?  (I can't think of any off hand, but I haven't tried very hard...)

Are you asking about functions that take variable number of arguments, or
functions like vprintf, that take an explicit va_list argument.

I don't think there's a vscanf(), though (it's not on my Solaris 2.6
system).

-- 
Barry Margolin, barmar@genuity.net
Genuity, Burlington, MA
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