From: Robert Klemme <shortcutter@...>
Date: 2011-12-05T21:11:36+09:00
Subject: Re: Stupid question

On Mon, Dec 5, 2011 at 12:17 PM, Sylvester Keil
<sylvester.keil@gmail.com> wrote:
>
> On Dec 5, 2011, at 11:38 AM, Robert Klemme wrote:
>
>> On Mon, Dec 5, 2011 at 10:03 AM, James Gallagher
>> <lollyproductions@mac.com> wrote:
>>> Thank you everyone for Helping me out.  :-)
>>
>> If I am not mistaken, everybody in this thread resorted to using a
>> string conversion.  Why does nobody want to calculate this
>> numerically?
>
> I posted a similar version to yours which uses an iterator.

Oh, I'm sorry I overlooked that one.

> n = 2011
> n.size.pred.downto(0).reduce(0) { |sum, a| sum += (n.abs / 10 ** a) % 10 }
>
> The while loop is more straightforward though. Perhaps we could combine the two?

I'm afraid your solution with Fixnum#size works only accidentally
because it returns the byte size of the number which coindicentally is
also the number of digits.  It fails for other values:

>> n = 90000
=> 90000
>> n.size.pred.downto(0).reduce(0) { |sum, a| sum += (n.abs / 10 ** a) % 10 }
=> 0
>> n.size
=> 4

Kind regards

robert

-- 
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