From: William James <w_a_x_man@...>
Date: 2009-02-11T16:48:59+09:00
Subject: Re: how to do the recursion

Li Chen wrote:

> William James wrote:
> 
> >> If you found Pascal's code somewhat puzzling, let me explain.
> > His customary language is CLisp, so when he deigns to dabble
> > in Ruby, he tries to make his code look lispish.
> 
> 
> Hi Will,
> 
> Thank you for your rubyish code.
> 
> Yes. I am really confused when I read Pascal's codes. I don't think 
> nowhere in Pixaxe ever mentions about function BUT only methods and 
> objects!
> 
> I have questions about two code lines:
> 1) result <<
> 
> What does it mean, concatenate nothing???

That line is not complete by itself.  The following lines provide
either 1 or 0 to be concatenated.

> 
> 2) num.odd?
> When I run the code Ruby complains about #odd?. I check the class
> Fixnum and I can't find #odd? So I change it to num%2==1 and Ruby
> runs happily.


It works with ruby 1.8.7 (2008-05-31 patchlevel 0).  You may have an
older version.

> 
> 
> Thanks,
> 
> Li
> 
> 
> > 
> > def dec_to_binary num, result = []
> >   result <<
> >     if num.odd?
> >       1
> >     else
> >       0
> >     end
> >   if num < 2
> >     result.reverse.join ""
> >   else
> >     dec_to_binary num/2, result
> >   end
> > end
> > 
> > 
> > p dec_to_binary 254



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