Convert number to list of digits

Question

How do I convert a number to a list of digits?

I am currently doing:

;; (num->list 12345) -> \'(1 2 3 4 5)
(define (num->list n)
  (local 
          


        

Answer 1

This is the digits function of my Standard Prelude:

(define (digits n . args)
  (let ((b (if (null? args) 10 (car args))))
    (let loop ((n n) (d '()))
      (if (zero? n) d
          (loop (quotient n b)
                (cons (modulo n b) d))))))

Your version of the function goes back-and-forth between strings and numbers; my version is purely arithmetic. My version also provides for bases other than decimal.