On Thu, 29 Jun 2006, Matthias Andree wrote: MA>Johannes Weiner <[EMAIL PROTECTED]> writes: MA> MA>> On Thu, Jun 29, 2006 at 06:09:37PM +0200, Matthias Andree wrote: MA>> MA>>> The value returned from malloc(0) must not be dereferenced whatever it MA>>> was. It was 0x800, which doesn't count as "failure". MA>> MA>> But this would be appropriate for catching the error: MA>> MA>> if ((foo = malloc(0)) == foo) MA>> /* make noise */ MA>> MA>> wouldn't it? MA> MA>No, sir. Operator precedence: assign first, and then compare, thus the MA>comparison will always be true (else you'd be comparing to undefined MA>values, which isn't any better). You might as well write:
Operator precedence is just for parsing, not for evaluation. The compiler may well first evaluate the foo on the right side of the == (by fetching it) and then go an call malloc and assign foo. It is actually undefined behaviour, I think, so it may well make explode your near-by atom power plant. harti MA> MA> foo = malloc(0); MA> /* make noise */ MA> MA>There is no way to see a 0x800 return from malloc(0) as "error". MA> MA> _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
