Non-decimal radices/Convert: Difference between revisions

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@@ Line 2,524: / Line 2,524: @@
  - : int = 26
-A real base conversion example: {{trans|Haskell}}
+A real base conversion implementation:
+<syntaxhighlight lang="ocaml">let basen_of_int b n : string =
+  let tab = "0123456789abcdefghijklmnopqrstuvwxyz" in
+  let rec aux x l =
+    if x < b
+    then tab.[x] :: l
+    else aux (x / b) (tab.[x mod b] :: l)
+  in
+  String.of_seq (List.to_seq (aux n []))
+let basen_to_int b ds : int =
-<syntaxhighlight lang="ocaml">let to_base b v =
-  let rec to_base' a v =
+  let of_sym c =
-    if v = 0 then
+    int_of_char c - match c with
+    | '0' .. '9' -> int_of_char '0'
-      a
+    | 'a' .. 'z' -> int_of_char 'a' - 10
-    else
-      to_base' (v mod b :: a) (v / b)
+    | 'A' .. 'Z' -> int_of_char 'A' - 10
+    | _ -> invalid_arg "unkown digit"
   in
+  String.fold_left (fun n d -> n * b + of_sym d) 0 ds</syntaxhighlight>
-    to_base' [] v
-let from_base b ds =
-  List.fold_left (fun n k -> n * b + k) 0 ds
-let to_alpha_digit n =
-  if n < 10 then
-    char_of_int (n + int_of_char '0')
-  else
-    char_of_int (n + int_of_char 'a' - 10)
-let to_alpha_digits ds =
-  let buf = Buffer.create (List.length ds) in
-    List.iter (fun i -> Buffer.add_char buf (to_alpha_digit i)) ds;
-    Buffer.contents buf
-let from_alpha_digit c = match c with
-    '0'..'9' -> int_of_char c - int_of_char '0'
-  | 'A'..'Z' -> int_of_char c - int_of_char 'A' + 10
-  | 'a'..'z' -> int_of_char c - int_of_char 'a' + 10
-let from_alpha_digits s =
-  let result = ref [] in
-    String.iter (fun c -> result := from_alpha_digit c :: !result) s;
-    List.rev !result</syntaxhighlight>
 Example:
 <pre>
-# to_alpha_digits (to_base 16 42);;
+# basen_of_int 16 26;;
-- : string = "2a"
+- : string = "1a"
-# from_base 16 (from_alpha_digits "2a");;
+# basen_to_int 16 "1a";;
-- : int = 42
+- : int = 26
 </pre>