From: Ara.T.Howard@...
Date: 2005-05-05T03:04:49+09:00
Subject: Re: Fixnum's binary representation

On Wed, 4 May 2005 camsight@gmail.com wrote:

> Hi, people!
>
> As far as I know, Ruby's Fixnum is 30-bit signed integer.
> One bit is used as a flag for whether it's a direct value.
> Another bit is used for non-Fixnum direct values.
> I wondered how Fixnum#[] works and tested it.
>
> def show_binary(i)
> 	result = ''
> 	32.times do |b|
> 		result = i[b].to_s + result
> 		if (b % 8 == 7) and (b != 31)
> 			result = " " + result
> 		end
> 	end
> 	puts result + ": " + i.to_s
> end
>
> show_binary(1)
> show_binary(-1)
> show_binary(2 ** 31 - 1)
> show_binary((2 ** 31 - 1) * (-1))
>
> Result:
>
> 00000000 00000000 00000000 00000001: 1
> 11111111 11111111 11111111 11111111: -1
> 01111111 11111111 11111111 11111111: 2147483647
> 10000000 00000000 00000000 00000001: -2147483647

don't deny yourself the joys of printf ;-)

   harp:~ > cat a.rb
   [ (1), (-1), (2 ** 31 - 1), ((2 ** 31 - 1) * (-1)) ].each{|n| printf "%32.32b\n", n}

   harp:~ > ruby a.rb
   00000000000000000000000000000001
   11111111111111111111111111111111
   01111111111111111111111111111111
   10000000000000000000000000000001

cheers.

-a
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