From: ara.t.howard@...
Date: 2005-11-29T02:41:08+09:00
Subject: Re: How to read/write an int in binary form to a file?

On Mon, 28 Nov 2005, speechexpert wrote:

> I did - but could see no way to pack a binary string. Is there a way to pack
> a binary string of bytes?


   harp:~ > irb
   irb(main):001:0> byte_string = [0,0,0,42].map{|c| c.chr}.join
   => "\000\000\000*"

   irb(main):002:0> byte_string.size
   => 4

   irb(main):003:0> byte_string.unpack('N').first
   => 42


strings are already packed.  if you want to treat a string as a collection of
bytes do

   harp:~ > irb
   irb(main):001:0> byte_string = [0,0,0,42].map{|c| c.chr}.join
   => "\000\000\000*"

   irb(main):002:0> bytes = byte_string.split(%r//).map{|b| b[0]}
   => [0, 0, 0, 42]

   irb(main):003:0> a = bytes.pack 'c*'
   => "\000\000\000*"

   irb(main):004:0> a.unpack('N').first
   => 42

hopefully you can figure out what to do from the above.

kind regards.

-a
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