# [erlang-questions] Bitstring question

Mike Oxford <>
Wed Feb 12 08:09:46 CET 2014

```interesting.  So why doesn't bitstring concatenation work in this case?
Should it?

On Tue, Feb 11, 2014 at 11:05 PM, Karolis Petrauskas <
> wrote:

> The "/bits" says, that the argument is bitstring.
> The "0:2" says, its an integer who's size is 2 bits. And "0" here is
> an integer, not a bitstring.
>
> Karolis
>
> On Wed, Feb 12, 2014 at 9:01 AM, Mike Oxford <> wrote:
> > Thank you!
> > But ...
> >
> > 64> <<0:2/bits, D/bits>>.
> > ** exception error: bad argument
> > 65> <<0:2, D/bits>>.
> > <<"!">>
> >
> > ??  Why does explicitly qualifying the 0:2 with /bits cause it to fail?
> >
> >
> >
> >
> >
> >
> > On Tue, Feb 11, 2014 at 10:41 PM, Karolis Petrauskas
> > <> wrote:
> >>
> >> 1> D = <<33:6>>.
> >> <<33:6>>
> >> 3> E = <<0:2, D/bits>>.
> >> <<"!">>
> >> 5> <<F>> = E.
> >> <<"!">>
> >> 6> F.
> >> 33
> >>
> >> Karolis
> >>
> >> On Wed, Feb 12, 2014 at 8:36 AM, Mike Oxford <> wrote:
> >> > << 0:2, D >> should concat the two.  Erlang knows what D is.
> >> > <<0:2/bits, D:6/bits>> should construct a single 8-bit value.
> >> > <<D/integer>> should (IMO) be valid because the value (33) is within
> the
> >> > range of /integer
> >> >
> >> > How would you convert it back out to 33?
> >> >
> >> >
> >> > On Tue, Feb 11, 2014 at 10:32 PM, Dmitry Kolesnikov
> >> > <>
> >> > wrote:
> >> >>
> >> >> Hello,
> >> >>
> >> >>
> >> >> Best Regards,
> >> >> Dmitry >-|-|-(*>
> >> >>
> >> >>
> >> >> > On 12.2.2014, at 8.27, Mike Oxford <> wrote:
> >> >> >
> >> >> > D = <<33:6>>
> >> >> > <<33:6>>
> >> >> D is length 6 bit
> >> >> >
> >> >> > I want to convert that 6 bit value (33) into a numeric value.
> >> >> >
> >> >> > Why does <<0:2, D>> not work?
> >> >> Type and size is not specified
> >> >> > Why does <<0:2/bits, D:6/bits>> not work?
> >> >> Expected size is 8 bits but your bit string is 6
> >> >> > Why does <<D/integer>> not work?
> >> >> Integer is 32bit
> >> >>
> >> >> >
> >> >> > Thanks in advance!
> >> >> >
> >> >> >
> >> >> >
> >> >> > _______________________________________________
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> >> >> >
> >> >> > http://erlang.org/mailman/listinfo/erlang-questions
> >> >
> >> >
> >> >
> >> > _______________________________________________
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> >> >
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> >> >
> >
> >
>
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