[erlang-questions] sorting rules regarding bit strings

David Mercer <>
Thu Apr 2 15:01:58 CEST 2009


On April 02, 2009, Ulf Wiger wrote:

> Maybe I'm just unusually dense today, but what are
> the sorting properties of bit strings?
. . .
> Well, I think I can see the pattern, but is this really
> what one wants?

The sort order seems right to me.  When I write out the bit patterns it
might make it clear:

> [<<1>>,    00000001
>   <<1>>,   00000001
>   <<1:7>>, 0000001
>   <<1:6>>, 000001
>   <<1:5>>, 00001
>   <<1:4>>, 0001
>   <<16>>,  00010000
>   <<1:3>>, 001
>   <<2:4>>, 0010
>   <<1:2>>, 01
>   <<2:3>>, 010
>   <<1:1>>, 1
>   <<2:2>>, 10
>   <<128>>, 10000000
>   <<"ÿ">>] 11111111

Sorting is done bit-by-bit, with end-of-bitstring < 0 < 1.

Or am I just weird, thinking that that is intuitive?

David Mercer




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