[Nick Maclaren] >>>> Firstly, a FAR more common assumption is that integers wrap in twos' >>>> complement - Python does not do that.
[Grant Edwards] >>> It used to [Fredrik Lundh] >> for integers ? what version was that ? [Grant] > Am I remebering incorrectly? Mostly but not entirely. > Didn't the old fixed-width integers operate modulo-wordsize? Not in Python. > I distinctly remember having to rewrite a bunch of checksum code when > fixed-width integers went away. Best guess is that you're working on a 32-bit box, and remember this Python <= 2.2 behavior specific to the left shift operator: >>> 1 << 31 -2147483648 >>> 1 << 32 0 On a 64-bit box (except Win64, which didn't exist at the time ;-)), those returned 2**31 and 2**32 instead, while "1 << 64" wrapped to 0 (etc). Python 2.3 starting warning about that: >>> 1 << 31 __main__:1: FutureWarning: x<<y losing bits or changing sign will return a long in Python 2.4 and up -2147483648 and Python 2.4 started producing platform-independent results: >>> 1 << 31 2147483648L >>> 1 << 32 4294967296L + - * / on short ints always complained about overflow before int-long unification, although IIRC very early Pythons missed the overflow error in (on a 32-bit box) int(-(2L**31))/-1. -- http://mail.python.org/mailman/listinfo/python-list
