questions - calling matheval() for printf

[Oliver Kiddle <okiddle@xxxxxxxxxxx>]

I have a few questions related to the use of matheval() for numeric
arguments to printf. According to the POSIX definition (which you can
read at http://www.opengroup.org/onlinepubs/007908799/xcu/printf.html),
with the %d format specification, and assuming 32-bit ints, the
following are the expect results:

argument	stdout		stderr
5a		5		printf: "5a" not completely converted
9999999999	2147483647	printf: "9999999999" arithmetic overflow
-9999999999	-2147483648	printf: "-9999999999" arithmetic overflow
ABC		0		printf: "ABC" expected numeric value

In the first case, the different error message doesn't worry me but
math evaluation doesn't return `5'. It is conceivable that someone
relies on this in a script, passing a string starting with a number and
redirecting stderr. I could successively chop characters off the right
of the string until matheval returns without an error. This would need
a hack to avoid repeated error messages from matheval(). Any other,
perhaps better suggestions?

Is there any way I can find out when arithmetic overflows have occurred
for the second and third cases? matheval() just allows the numbers to
wrap?

In the last case, we'll just have to be non-compliant (it returns $ABC)
but that doesn't worry me much.

What is going on with this errval and zerr/zwarn stuff? I don't
entirely understand which I should be calling on errors and whether I
am right to zero errval after calling matheval() and reading it?

Can a 64-bit integer be something other than long long? It seems I only
have ZSH_64_BIT_TYPE to check and it might need a different format
specifier for printf(3) if this is something other than long long.

Aside from this, using matheval() works very smoothly and it is
certainly better that we won't lose precision due to converting floats
via ASCII before formatting..

Oliver