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From: Uri Guttman on 1 Mar 2010 13:47
>>>>> "OA" == Oscar Almer <o.almer(a)sms.ed.ac.uk> writes:

OA> I seem to recall (I wrote some code that parses binary strings
OA> recently) that oct() does that, if you prefix it with "0b" to
OA> indicate binaryness. Some application of reverse / substr might be
OA> useful to handle byte ordering.

OA> I could be wrong.

you are wrong. :)

she has real binary bytes. 0b deals with bits in ascii form.

uri

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From: Oscar Almer on 1 Mar 2010 13:43
On Mon, 01 Mar 2010 19:17:54 +0100
Looden <no.mail(a)spam.no> wrote:

> Hi
> I'm parsing a binary string, which encodes a number.
> I don't know the length of the string in advance: 1, 2, 3 or 4 bytes.
> The bytes of the string are in network order.
> How can I retrieve the number?
>
> I've written this sub, there must be a better way:
>
> sub parse_number {
> my $arg = shift;
> my $size = length($arg);
> my $value = 0;
> my $buf;
> for (my $i=($size-1);$i>=0;$i--){
> $buf = unpack "C", (substr $arg, $i, 1);
> $value += $buf * (256**($size-$i-1));
> }
> return $value;
> }
>
> Note: If the length of the string was always 2 bytes, I could just
> do: sub parse_n { return unpack "n", shift; }
>
> Thanks in advance.
>

I seem to recall (I wrote some code that parses binary strings recently)
that oct() does that, if you prefix it with "0b" to indicate
binaryness. Some application of reverse / substr might be useful to
handle byte ordering.

I could be wrong.

//Oscar
From: Oscar Almer on 1 Mar 2010 13:53
On Mon, 01 Mar 2010 13:47:35 -0500
"Uri Guttman" <uri(a)StemSystems.com> wrote:


> OA> I could be wrong.
>
> you are wrong. :)
>
> she has real binary bytes. 0b deals with bits in ascii form.
>
> uri
>

Ah, My bad.

I apologize and retract the previous.

//Oscar

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