Re: integer divided by zero

Thiago Adams <thiago.adams@gmail.com> writes:

Does anyone know of any platform where integer division by zero
returns a number, or in other words, where it's not treated as an
error? I'm asking because division by zero is undefined behaviour, but
I think division by a constant zero should be a constraint instead.

Division by a constant zero is a constraint violation in a context that
requires a constant expression.

I wrote this quick and dirty program:

#include <stdio.h>
#include <time.h>
int main(void) {
    int one = time(NULL) / 1000000000;
    int zero = one - 1;
    int ratio = one / zero;
    printf("%d\n", ratio);
}

It's not portable, but on the systems where I've tried it it sets
one to 1 and zero to 0 in a way that the compiler can't detect,
so the division won't be optimized away.  (At least, it does so if
you run it between 2001 and 2286.)

On x86_64, it dies with a floating point exception.

On aarch64, it prints 0.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */