Wrapping variable length agument lists

[Sisyphus]

Hi,
Suppose I wanted to write a wrapper for the C printf() function - 
something like:

use warnings;
use Inline C => <<'EOC';
void wrap_printf(SV * a, SV * b) {
     if(SvUOK(b)) printf(SvPV_nolen(a), SvUV(b));
     if(SvIOK(b)) printf(SvPV_nolen(a), SvIV(b));
     if(SvNOK(b)) printf(SvPV_nolen(a), SvNV(b));
}
EOC
$x = -32;
$y = 40;
wrap_printf("%d\n", $x);
wrap_printf("%#o\n", $y);
That would work fine (up to a point) - but, of course, instead of 
writing the wrap_printf() function twice, I would want to do it as one 
function call, just as you would with the printf() function:

wrap_printf("%d\n%#o\n", $x, $y);
That, of course, no longer works. The wrap_printf() function needs to be 
able to accommodate argument lists of varying lengths - so I thought:

void wrap_printf(SV * a, ...) {
/* Code to transfer the supplied arguments to C's printf() function */
}
The only trouble now is that I don't know what that "Code" looks like 
and whether that "Code" can be written in a way that performs efficiently.

So now I'm thinking that wrap_printf() needs to take a reference to an 
array as its argument:

void wrap_printf(AV * arguments) {
/* Code to transfer the referred arguments to C's printf() function */
}
I don't know, off the top of my head, exactly what *that* "Code" looks 
like either - though I'm confident I can work it out.

A slight problem with this last rendition is that one will now have to 
call wrap_printf() from perl as:

wrap_printf(["%d\n%#o\n", $x, $y]);
which is different to the usual printf() argument format - which would 
be unfortunate, though tolerable.

Any thoughts on what is the *correct* approach would be appreciated.
(The correct approach is to use perl's printf() function - but let's 
suppose, for the sake of argument, that perl doesn't have one. I guess 
that there's also some code somewhere in the perl source that would go a 
long way towards showing me the best way to go about it, but I'm a bit 
overwhelmed when it comes to actually locating that source code.)

Cheers,
Rob