Data commit

Task/Non-decimal-radices-Convert/Racket/non-decimal-radices-convert.rkt

@@ -0,0 +1,21 @@
+#lang racket
+
+;; Both assume valid inputs
+(define (num->str N r)
+  (let loop ([N N] [digits '()])
+    (define-values [N1 d] (quotient/remainder N r))
+    (define digits1 (cons (integer->char (+ d (if (< d 10) 48 55))) digits))
+    (if (zero? N) (list->string digits1) (loop N1 digits1))))
+(define (str->num S r)
+  (for/fold ([N 0])
+            ([B (string->bytes/utf-8 (string-upcase S))])
+    (+ (* N r) (- B (if (< 64 B) 55 48)))))
+
+;; To try it out:
+(define (random-test)
+  (define N (random 1000000))
+  (define r (+ 2 (random 35)))
+  (define S (num->str N r))
+  (define M (str->num S r))
+  (printf "~s -> ~a#~a -> ~a => ~a\n" N S r M (if (= M N) 'OK 'BAD)))
+;; (random-test)