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.
-Steve
