On Monday, 15 December 2014 at 15:19:25 UTC, Steven Schveighoffer
wrote:
On 12/13/14 5:47 AM, "Marc =?UTF-8?B?U2Now7x0eiI=?=
<schue...@gmx.net>" wrote:
On Friday, 12 December 2014 at 19:35:26 UTC, Steven
Schveighoffer wrote:
On 12/12/14 2:17 PM, H. S. Teoh via Digitalmars-d-learn wrote:
I've started working on an implementation of this... but
it's not very
clear what the correct semantics should be. For example, if
my starting
BitArray b is 1101, say, what should be the result after
b>>=1? Should
it be 0110, 110, or 01101?
0110
In other words, I would assume the same semantics as an
unsigned int.
In other other words, it's like each bit moves one to the
right, and
the bit that has no source gets a 0.
There's a dedicated >>> operator for unsigned right shift, the
normal >>
operator does a signed right shift, i.e. it copies the
left-most bit:
http://dlang.org/expression#ShiftExpression
IMO, for consistency, bitarray should behave the same.
But BitArray is not signed, it's an array of bits, none of
which are signed or designated as the sign bit. The unsigned
shift operator is only for signed integral types, for unsigned
values >> is simply a shift of bits. Note that your assertion
that >> "copies the left-most bit" is not in the text, and is
incorrect. It copies the sign bit, which doesn't exist in an
unsigned type.
I think >> and >>> should do the same thing, and be unsigned
shifts on BitArray.
Yes, yebblies pointed that out in the PR. I was confused, because
the documentation doesn't say that `>>` and `>>>` only behave
differently for signed integers.
