From: "Mauricio Fernández" <batsman.geo@...>
Date: 2003-07-19T04:36:23+09:00
Subject: Re: [SNIPPET] Binary counter

On Sat, Jul 19, 2003 at 04:05:39AM +0900, Phil Tomson wrote:
> I needed to test a class which had a certain number of 'binary' inputs (ie. each input 
> takes either 0 or 1 (or false or true) ).  In order to do this I needed to try out every 
> possible combination of inputs - essentially a binary count, like:
> 
> 0,0,0,0
> 0,0,0,1
> ....
> 1,1,1,0
> 1,1,1,1
> 
> I figured I could just increment an integer and, then convert it to binary, but:
>   1) there doesn't seem to be a builtin to_bin method on FixNum.
>   2) I'd still have to deal with indexing, etc.
>   (OK, it wouldn't be that hard to implement #1 and #2 is not that hard either, but I 
> decided to go a different route for fun ;-)

>> 8.times {|i| 4.times {|j| print i[3-j]}; puts }
0000
0001
0010
0011
0100
0101
0110
0111
=> 8
>> class Fixnum; def to_bin(bits=31); a = []; bits.times{|i| a.unshift self[i]}; a end end
=> nil
>> 10.times {|i| p i.to_bin(4)}
[0, 0, 0, 0]
[0, 0, 0, 1]
[0, 0, 1, 0]
[0, 0, 1, 1]
[0, 1, 0, 0]
[0, 1, 0, 1]
[0, 1, 1, 0]
[0, 1, 1, 1]
[1, 0, 0, 0]
[1, 0, 0, 1]


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