On 2016-06-22, Random832 <random...@fastmail.com> wrote: > On Wed, Jun 22, 2016, at 10:19, Grant Edwards wrote: > >> Is that guaranteed by Python, or just a side-effect of the >> implementation? Back in the days when Python used native C >> integers I think the latter. > > AIUI, native C integers have never reliably supported signed zero > even with representations that naively seem to have it. There's no > well-defined way to detect it - no int version of copysign, for > instance - and implementations are free to erase the distinction on > every load/store or define one of them to be a trap representation.
It's been almost 25 years since I used hardware that supported signed zero integers (CDC 6600). I don't recall there being a C compiler available. We used Pascal and assembly, though I think FORTRAN was what most people used. I don't recall whether the Pascal implementation exposed the existence of -0 to the user or not. I'm pretty certain there wasn't a Python implementation... -- Grant Edwards grant.b.edwards Yow! Loni Anderson's hair at should be LEGALIZED!! gmail.com -- https://mail.python.org/mailman/listinfo/python-list