Tim Peters <tim.pet...@gmail.com> added the comment: Terry, the language reference also says:
""" For the purpose of shift and mask operations, a binary representation is assumed, and negative numbers are represented in a variant of 2's complement which gives the illusion of an infinite string of sign bits extending to the left. """ That explains every result you saw: 3 = ...000011 2 = ...000010 1 = ...000001 -3 = ...111101 2 = ...000010 -1 = ...111111 3 = ...000011 -2 = ...111110 -3 = ...111101 -3 = ...111101 -2 = ...111110 3 = ...000011 2 = ...000010 3 = ...000011 1 = ...000001 -2 = ...111110 3 = ...000011 -3 = ...111101 In every case, the result is simply the xor of the inputs viewed as infinite bitstrings. And it works exactly the same way if you use |, &, <<, >>, or unary ~. It's true that CPython's longs are /implemented/ via sign-magnitude, but that should never be visible in the result of any operation. ---------- nosy: +tim_one _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue7406> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
