As I discovered, when porting the Ruby big-integer unit tests to C# to test a BigInteger class --
Answer: Sometimes but not always, when x is negative and odd.
Python and Ruby -- native and DLR -- do maintain the identity:
IronPython 1.1.1 (1.1.1) on .NET 2.0.50727.1433 Copyright (c) Microsoft Corporation. All rights reserved. >>> i = -57 >>> a = i/2 >>> b = i>>1 >>> print a,b -29 -29
version 2.0β2, IronRuby pre-alpha, Python 2.5.2, Ruby 1.8.6 equivalents all omitted.
Indeed the Ruby big-integer unit tests contain a couple of tests explicitly to assert this identity. But doinggives
/2 -> -28; >>1 -> -29
following the 'C' family "round towards zero" approach.
This is a potential peril in polyglot programming within an application -- the "same" arithmetic expression can yield different results depending on the language being used locally. Just being on the CLR, for example, does not mandate your arithmetic -- the language definition does. This is not something that one would at first consider might happen.