IBAN: Difference between revisions

=={{header|Standard ML}}==

{{works with|SML/NJ}}

<lang sml>(* country_code : string -> int *)

(* Get the length of a valid IBAN given the two chars long country code *)

fun country_code (str : string) : int =

case str of

"AL" => 28 | "AD" => 24 | "AT" => 20 | "AZ" => 28

| "BE" => 16 | "BH" => 22 | "BA" => 20 | "BR" => 29

| "BG" => 22 | "CR" => 21 | "HR" => 21 | "CY" => 28

| "CZ" => 24 | "DK" => 18 | "DO" => 28 | "EE" => 20

| "FO" => 18 | "FI" => 18 | "FR" => 27 | "GE" => 22

| "DE" => 22 | "GI" => 23 | "GR" => 27 | "GL" => 18

| "GT" => 28 | "HU" => 28 | "IS" => 26 | "IE" => 22

| "IL" => 23 | "IT" => 27 | "KZ" => 20 | "KW" => 30

| "LV" => 21 | "LB" => 28 | "LI" => 21 | "LT" => 20

| "LU" => 20 | "MK" => 19 | "MT" => 31 | "MR" => 27

| "MU" => 30 | "MC" => 27 | "MD" => 24 | "ME" => 22

| "NL" => 18 | "NO" => 15 | "PK" => 24 | "PS" => 29

| "PL" => 28 | "PT" => 25 | "RO" => 24 | "SM" => 27

| "SA" => 24 | "RS" => 22 | "SK" => 24 | "SI" => 19

| "ES" => 24 | "SE" => 24 | "CH" => 21 | "TN" => 24

| "TR" => 26 | "AE" => 23 | "GB" => 22 | "VG" => 24

| _ => raise Domain

(* removespace : string -> string *)

(* Removes all spaces from a string *)

fun removespace s = String.translate (fn #" " => "" | c => str c) s

(* to_upper : string -> string *)

(* Convert every char to upper of a string *)

fun to_upper (s : string) : string =

String.translate (fn c => str (Char.toUpper c)) s

(* convert_to_number : char -> string *)

(* Covert a alphanumeric char into a numerical string *)

fun convert_to_number (c : char) : string =

if Char.isDigit c then str c else

if Char.isUpper c then Int.toString (10 + ord c - ord #"A") else

raise Domain

(* verify_iban : string -> bool *)

(* Check weather a string is a valid IBAN *)

fun verify_iban str =

let

(* Remove spaces and make upper case *)

val str = to_upper (removespace str)

(* Fetch first two chars (country code) *)

val country = String.substring (str, 0, 2)

val len = country_code country

in

(* size test *)

String.size str = len

andalso

(* Every char must be alphanumeric *)

List.all Char.isAlphaNum (explode str)

andalso

let

(* Reorder *)

val str = String.substring (str, 4, String.size str - 4) ^ String.substring (str, 0, 4)

(* Convert into digits *)

val str = String.translate convert_to_number str

(* Convert into a big number *)

val number = valOf (IntInf.fromString str)

in

IntInf.mod (number, 97) = 1

end

end handle Subscript => false | Domain => false</lang>

{{output}}

<pre>- verify_iban "GB82 WEST 1234 5698 7654 32";

val it = true : bool

- verify_iban "GB82 TEST 1234 5698 7654 32";

val it = false : bool</pre>