i figured i can count the number of bits set for a BitArray with std.algorithm : count:

BitArray([0,0,1]).bitsSet.count()

but this seems not very optimal, is there a faster way directly accessible trough phobos?

ideally something that is optimized by the compiler.

On Tuesday, 1 March 2016 at 09:03:47 UTC, yawniek wrote:
> i figured i can count the number of bits set for a BitArray with std.algorithm : count:
>
> BitArray([0,0,1]).bitsSet.count()
>
> but this seems not very optimal, is there a faster way directly accessible trough phobos?
>
> ideally something that is optimized by the compiler.

Maybe you should look for "hamming weight" :)

On Tuesday, 1 March 2016 at 09:32:20 UTC, Andrea Fontana wrote:
> Maybe you should look for "hamming weight" :)
maybe. and here is a snowman for you: ☃

the question was if it exists for BitArray in phobos.

https://issues.dlang.org/show_bug.cgi?id=10239 so apparently its really missing in phobos BitArray. the algo is even described in TDPL.