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comp.lang.ruby

Question about digits

Rubén Medellín

1/27/2007 11:35:00 PM

While playing a little with Ruby, I've been looking for a function
each_digit, or something similar, and I couldn't find any (standard
nor library). I think it'd be useful to have a function like that.
It's pretty simple to implement one for Integers

class Integer
def each_digit(base = 10, &block)
return if zero?
(self/base).each_digit(base, &block)
yield self % base
end
end

A first approach. Of course, it would be a little more complicated for
negatives and Floats, specially dealing with precision.

What do you think?
3 Answers

Xavier Noria

1/28/2007 12:03:00 AM

0

On Jan 28, 2007, at 12:35 AM, CHubas wrote:

> While playing a little with Ruby, I've been looking for a function
> each_digit, or something similar, and I couldn't find any (standard
> nor library). I think it'd be useful to have a function like that.
> It's pretty simple to implement one for Integers
>
> class Integer
> def each_digit(base = 10, &block)
> return if zero?
> (self/base).each_digit(base, &block)
> yield self % base
> end
> end
>
> A first approach. Of course, it would be a little more complicated for
> negatives and Floats, specially dealing with precision.

Good. I'd expect each_digit to return strings though, since a digit
is a symbol, not a number:

class Integer
def each_digit(base=10)
abs.to_s(base).each_byte do |b|
yield b.chr
end
end
end

-- fxn

Fer#

1/28/2007 12:11:00 AM

0

Why call them digits, if you can call them characters?

If you have got arbitrary_number, you got arbitrary_number.to_s so:

----
irb(main):001:0> arbitrary_number=123
=> 123
irb(main):002:0> arbitrary_number.to_s
=> "123"
irb(main):002:0> arbitrary_number.to_s.length
=> 3
irb(main):003:0> (0...arbitrary_number.to_s.length).map{|digit|
arbitrary_number.to_s.split('')[digit]}
=> ["1","2","3"]
----

This above will do for base 10, and printf stuff may help with hex,
oct at least.

Remember it is '...' and not '..' so you don't access
arbitrary_number[arbitrary_number.length]

Hope this may help you

Vidar Hokstad

1/28/2007 1:24:00 PM

0

On Jan 28, 12:10 am, "Fer#" <fernando.mdelacu...@gmail.com> wrote:
> Why call them digits, if you can call them characters?
>
> If you have got arbitrary_number, you got arbitrary_number.to_s so:
[... snip]
> This above will do for base 10, and printf stuff may help with hex,
> oct at least.

Actually, Fixnum#to_s and Bignum#to_s takes optional arguments
specifying base, so to handle hex you'd do arbitrary_number.to_s(16)
etc.

Vidar