On Feb 17, 11:09 am, Ken Wesson <kwess...@gmail.com> wrote:
> On Thu, Feb 17, 2011 at 12:29 AM, Andreas Kostler
>
> <andreas.koestler.le...@gmail.com> wrote:
> > Is there an easy and idiomatic way of getting the digits of a number in
> > clojure?
>
> > (defn explode-to-digits [number]
> > (map #(- (int %) (int \0)) (str number)))
> > (explode-to-digits 123456)
> > => (1 2 3 4 5 6)
>
> > Seems a bit clunky...
>
> How about
>
> (defn explode-to-digits [n]
> (if (= n 0)
> []
> (let [d (rem n 10)
> r (quot n 10)]
> (conj (explode-to-digits r) d))))
>
> or if you want to avoid consuming stack
>
> (defn explode-to-digits* [n out]
> (if (= n 0)
> out
> (let [d (rem n 10)
> r (quot n 10)]
> (recur r (cons d out)))))
>
> (defn explode-to-digits [n]
> (explode-to-digits* n nil))
>
> It should also be possible to make a lazy sequence version, but
> returning the digits in the reverse order.
A bit shorter:
(defn digits [n]
(let [r (rem n 10)
q (int (/ n 10))
_ (println (format "q=%d, r=%d" q r))]
(if (zero? q) [r]
(into [r] (digits q)))))
Not efficient though.
Regards,
Shantanu
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