From: William James <w_a_x_man@...>
Date: 2009-02-11T16:43:48+09:00
Subject: Re: how to do the recursion

Li Chen wrote:

> William James wrote:
> 
> > 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
> 
> 
> Hi Will,
> 
> I have one more question about the method call:
> 
> When you define method dec_to_binary, you pass two parameters.
> But when you call the method, you only provide one parameter.
> 
> Surprisingly Ruby doesn't complain it. How to explain this seemly 
> inconsistancy?
> 
> Thanks,
> 
> Li

I told dec_to_binary to use the default value [] for result
when no value for result is passed to the function:

def dec_to_binary num, result = []
                              ^^^^