ISBN13 check digit: Difference between revisions
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{{task}}
;Task:
Validate the check digit of an ISBN-13 code:
::* Multiply every other digit by '''3'''.
::* Add these numbers and the
::* Take the remainder of this number after division by '''10'''.
::* If it is '''0''', the ISBN-13 check digit is correct.
::::* 978-
::::* 978-
::::* 978-1788399081 (good)
::::* 978-1788399083 (bad)
Line 20:
;See also:
:* for details: [https://isbn-information.com/the-13-digit-isbn.html 13-digit ISBN method of validation]. (
<br><br>
=={{header|11l}}==
{{trans|Python}}
<syntaxhighlight lang="11l">F is_isbn13(=n)
n = n.replace(‘-’, ‘’).replace(‘ ’, ‘’)
I n.len != 13
R 0B
V product = sum(n[(0..).step(2)].map(ch -> Int(ch)))
+ sum(n[(1..).step(2)].map(ch -> Int(ch) * 3))
R product % 10 == 0
V tests = |‘978-0596528126
978-0596528120
978-1788399081
978-1788399083’.split("\n")
L(t) tests
print(‘ISBN13 ’t‘ validates ’is_isbn13(t))</syntaxhighlight>
{{out}}
<pre>
ISBN13 978-0596528126 validates 1B
ISBN13 978-0596528120 validates 0B
ISBN13 978-1788399081 validates 1B
ISBN13 978-1788399083 validates 0B
</pre>
=={{header|8080 Assembly}}==
<
jmp demo
;;; ---------------------------------------------------------------
Line 91 ⟶ 118:
jmp 5
good: db 'good$'
bad: db 'bad$'</
{{out}}
<pre>A>isbn13 978-
good
A>isbn13 978-
bad
A>isbn13 978-1788399081
Line 106 ⟶ 133:
=={{header|8086 Assembly}}==
<
bits 16
org 100h
Line 159 ⟶ 186:
section .data
good: db 'good$'
bad: db 'bad$'</
{{out}}
<pre>C:\>isbn13 978-
good
C:\>isbn13 978-
bad
C:\>isbn13 978-1788399081
Line 171 ⟶ 198:
C:\>isbn13 978-1788399083
bad</pre>
=={{header|ABC}}==
<syntaxhighlight lang="abc">HOW TO REPORT valid.isbn13 str:
PUT {} IN digits
FOR d IN {0..9}: PUT d IN digits["`d`"]
IF #str <> 14 OR str item 4 <> '-': FAIL
PUT 1, 0 IN mul, sum
FOR c IN str|3 ^ str@5:
IF c not.in keys digits: FAIL
PUT sum + digits[c] * mul IN sum
PUT 4 - mul IN mul
REPORT sum mod 10 = 0
PUT {} IN tests
PUT "978-0596528126" IN tests[1]
PUT "978-0596528120" IN tests[2]
PUT "978-1788399081" IN tests[3]
PUT "978-1788399083" IN tests[4]
FOR test IN tests:
SELECT:
valid.isbn13 test: WRITE test^": good"/
ELSE: WRITE test^": bad"/</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|Action!}}==
{{libheader|Action! Tool Kit}}
<syntaxhighlight lang="action!">INCLUDE "D2:CHARTEST.ACT" ;from the Action! Tool Kit
BYTE FUNC CheckISBN13(CHAR ARRAY t)
BYTE i,index,sum,v
sum=0 index=0
FOR i=1 TO t(0)
DO
v=t(i)
IF IsDigit(v) THEN
v==-'0
IF index MOD 2=1 THEN
v==*3
FI
sum==+v
index==+1
ELSEIF v#' AND v#'- THEN
RETURN (0)
FI
OD
IF index#13 OR sum MOD 10#0 THEN
RETURN (0)
FI
RETURN (1)
PROC Test(CHAR ARRAY t)
BYTE correct
correct=CheckISBN13(t)
Print(t) Print(" is ")
IF correct THEN
PrintE("correct")
ELSE
PrintE("incorrect")
FI
RETURN
PROC Main()
Put(125) PutE() ;clear screen
Test("978-0596528126")
Test("978-0596528120")
Test("978-1788399081")
Test("978-1788399083")
RETURN</syntaxhighlight>
{{out}}
[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/ISBN13_check_digit.png Screenshot from Atari 8-bit computer]
<pre>
978-0596528126 is correct
978-0596528120 is incorrect
978-1788399081 is correct
978-1788399083 is incorrect
</pre>
=={{header|Ada}}==
<syntaxhighlight lang="ada">with Ada.Text_IO;
procedure ISBN_Check is
function Is_Valid (ISBN : String) return Boolean is
Odd : Boolean := True;
Sum : Integer := 0;
Value : Integer;
begin
for I in ISBN'Range loop
if ISBN (I) in '0' .. '9' then
Value := Character'Pos (ISBN (I)) - Character'Pos ('0');
if Odd then
Sum := Sum + Value;
else
Sum := Sum + 3 * Value;
end if;
Odd := not Odd;
end if;
end loop;
return Sum mod 10 = 0;
end Is_Valid;
procedure Show (ISBN : String) is
use Ada.Text_IO;
Valid : constant Boolean := Is_Valid (ISBN);
begin
Put (ISBN); Put (" ");
Put ((if Valid then "Good" else "Bad"));
New_Line;
end Show;
begin
Show ("978-0596528126");
Show ("978-0596528120");
Show ("978-1788399081");
Show ("978-1788399083");
end ISBN_Check;</syntaxhighlight>
{{out}}
<pre>978-0596528126 Good
978-0596528120 Bad
978-1788399081 Good
978-1788399083 Bad</pre>
=={{header|ALGOL 68}}==
{{works with|ALGOL 68G|Any - tested with release 2.8.3.win32}}
<
# returns TRUE if the alledged isbn13 has the correct check sum, #
# FALSE otherwise #
Line 196 ⟶ 350:
END; # check isbn13 #
# task test cases #
[]STRING tests = ( "978-
[]BOOL expected = ( TRUE, FALSE, TRUE, FALSE );
FOR pos FROM LWB tests TO UPB tests DO
Line 208 ⟶ 362:
)
OD
END</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|APL}}==
{{works with|Dyalog APL}}
<syntaxhighlight lang="apl">check_isbn13←{
13≠⍴n←(⍵∊⎕D)/⍵:0
0=10|(⍎¨n)+.×13⍴1 3
}</syntaxhighlight>
{{out}}
<pre> check_isbn13¨ '978-0596528126' '978-0596528120' '978-1788399081' '978-1788399083'
1 0 1 0</pre>
=={{header|AppleScript}}==
===Composition of pure functions===
<
-- isISBN13 :: String -> Bool
Line 249 ⟶ 415:
end script
map(test, {"978-
"978-1788399081", "978-1788399083"})
end run
Line 424 ⟶ 590:
return lst
end tell
end zipWith</
{{Out}}
<pre>{{"978-
===Straightforward===
Line 432 ⟶ 598:
This task ''can'' be tackled very simply by working through the numeric text two characters at a time:
<
if (ISBN13's class is not text) then return false
Line 460 ⟶ 626:
set output to {}
set verdicts to {"bad", "good"}
repeat with thisISBN13 in {"978-
set isValid to validateISBN13(thisISBN13)
set end of output to thisISBN13 & ": " & item ((isValid as integer) + 1) of verdicts
Line 469 ⟶ 635:
set output to output as text
set AppleScript's text item delimiters to astid
return output</
{{output}}
<pre>"978-
978-
978-1788399081: good
978-1788399083: bad"</pre>
Line 479 ⟶ 645:
Or it can be handled purely numerically. Since the "weights" alternate and are palindromic, it makes no difference whether the last digit or the first is treated as the check digit. In fact, if preferred, the repeat below can go round 7 times with the <tt>return</tt> line as simply: <tt>return (sum mod 10 = 0)</tt>.
<
if (ISBN13's class is not text) then return false
Line 503 ⟶ 669:
return ((sum + ISBN13) mod 10 = 0)
end validateISBN13</
=={{header|Arturo}}==
<syntaxhighlight lang="rebol">validISBN?: function [isbn][
currentCheck: to :integer to :string last isbn
isbn: map split chop replace isbn "-" "" 'd -> to :integer d
s: 0
loop.with:'i isbn 'n [
if? even? i -> s: s + n
else -> s: s + 3*n
]
checkDigit: 10 - s % 10
return currentCheck = checkDigit
]
tests: [
"978-0596528126" "978-0596528120"
"978-1788399081" "978-1788399083"
]
loop tests 'test [
print [test "=>" validISBN? test]
]</syntaxhighlight>
{{out}}
<pre>978-0596528126 => true
978-0596528120 => false
978-1788399081 => true
978-1788399083 => false</pre>
=={{header|AutoHotkey}}==
<syntaxhighlight lang="autohotkey">ISBN13_check_digit(n){
for i, v in StrSplit(RegExReplace(n, "[^0-9]"))
sum += !Mod(i, 2) ? v*3 : v
return n "`t" (Mod(sum, 10) ? "(bad)" : "(good)")
}</syntaxhighlight>
Examples:<syntaxhighlight lang="autohotkey">output := ""
nums := ["978-0596528126","978-0596528120","978-1788399081","978-1788399083"]
for i, n in nums
output .= ISBN13_check_digit(n) "`n"
MsgBox % output
return</syntaxhighlight>
{{out}}
<pre>978-0596528126 (good)
978-0596528120 (bad)
978-1788399081 (good)
978-1788399083 (bad)</pre>
=={{header|AWK}}==
<syntaxhighlight lang="awk">
# syntax: GAWK -f ISBN13_CHECK_DIGIT.AWK
BEGIN {
arr[++n] = "978-
arr[++n] = "978-
arr[++n] = "978-1788399081"
arr[++n] = "978-1788399083"
Line 529 ⟶ 744:
return(substr(isbn,13,1) == check_digit ? "OK" : sprintf("NG check digit S/B %d",check_digit))
}
</syntaxhighlight>
{{out}}
<pre>
978-
978-
978-1788399081 OK
978-1788399083 NG check digit S/B 1
Line 539 ⟶ 754:
0820424528 NG length
</pre>
=={{header|BASIC256}}==
{{trans|Ring}}
<syntaxhighlight lang="vb">arraybase 1
dim isbn = {"978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083", "978-2-74839-908-0", "978-2-74839-908-5", "978 1 86197 876 9"}
for n = 1 to isbn[?]
sum = 0
isbnStr = isbn[n]
isbnStr = replace(isbnStr, "-", "")
isbnStr = replace(isbnStr, " ", "")
for m = 1 to length(isbnStr)
if m mod 2 = 0 then
num = 3 * int(mid(isbnStr, m, 1))
else
num = int(mid(isbnStr, m, 1))
end if
sum += num
next m
if sum mod 10 = 0 then
print isbn[n]; ": good"
else
print isbn[n]; ": bad"
end if
next n</syntaxhighlight>
=={{header|BCPL}}==
<syntaxhighlight lang="bcpl">get "libhdr"
let checkISBN(s) = valof
$( let tally = 0
unless s%0 = 14 resultis false
unless s%4 = '-' resultis false
for i=1 to 3
$( let digit = s%i-'0'
test i rem 2 = 0
do tally := tally + 3 * digit
or tally := tally + digit
$)
for i=5 to 14
$( let digit = s%i-'0'
test i rem 2 = 0
do tally := tally + digit
or tally := tally + 3 * digit
$)
resultis tally rem 10 = 0
$)
let show(s) be
writef("%S: %S*N", s, checkISBN(s) -> "good", "bad")
let start() be
$( show("978-0596528126")
show("978-0596528120")
show("978-1788399081")
show("978-1788399083")
$)</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|C}}==
<
int check_isbn13(const char *isbn) {
Line 567 ⟶ 847:
int main() {
int i;
const char* isbns[] = {"978-
for (i = 0; i < 4; ++i) {
printf("%s: %s\n", isbns[i], check_isbn13(isbns[i]) ? "good" : "bad");
}
return 0;
}</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
Line 584 ⟶ 864:
=={{header|C++}}==
{{trans|C}}
<
bool check_isbn13(std::string isbn) {
Line 613 ⟶ 893:
int main() {
auto isbns = { "978-
for (auto isbn : isbns) {
std::cout << isbn << ": " << (check_isbn13(isbn) ? "good" : "bad") << '\n';
Line 619 ⟶ 899:
return 0;
}</
{{out}}
<pre>978-
978-
978-1788399081: good
978-1788399083: bad</pre>
=={{header|C sharp}}==
<
using System.Linq;
Line 633 ⟶ 913:
{
public static void Main() {
Console.WriteLine(CheckISBN13("978-
Console.WriteLine(CheckISBN13("978-
Console.WriteLine(CheckISBN13("978-1788399081"));
Console.WriteLine(CheckISBN13("978-1788399083"));
Line 649 ⟶ 929:
}
}
}</
{{out}}
<pre>
Line 656 ⟶ 936:
True
False</pre>
=={{header|CLU}}==
<syntaxhighlight lang="clu">isbn13_check = proc (s: string) returns (bool)
if string$size(s) ~= 14 then return(false) end
if s[4] ~= '-' then return(false) end
begin
check: int := 0
for i: int in int$from_to(1, 14) do
if i=4 then continue end
d: int := int$parse(string$c2s(s[i]))
if i=2 cor (i>4 cand i//2=1) then d := d*3 end
check := check + d
end
return(check//10 = 0)
end except when bad_format:
return(false)
end
end isbn13_check
start_up = proc ()
po: stream := stream$primary_output()
tests: array[string] := array[string]$
["978-0596528126",
"978-0596528120",
"978-1788399081",
"978-1788399083"]
for test: string in array[string]$elements(tests) do
stream$puts(po, test)
stream$puts(po, ": ")
if isbn13_check(test)
then stream$putl(po, "good")
else stream$putl(po, "bad")
end
end
end start_up</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|COBOL}}==
{{works with|GnuCOBOL}}
<syntaxhighlight lang="cobol"> ******************************************************************
* Author: Jay Moseley
* Date: November 10, 2019
* Purpose: Testing various subprograms/ functions.
* Tectonics: cobc -xj testSubs.cbl
******************************************************************
IDENTIFICATION DIVISION.
PROGRAM-ID. testSubs.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
REPOSITORY.
FUNCTION ALL INTRINSIC
FUNCTION validISBN13.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
DATA DIVISION.
FILE SECTION.
WORKING-STORAGE SECTION.
01 IX PIC S9(4) COMP.
01 TEST-ISBNS.
02 FILLER PIC X(14) VALUE '978-0596528126'.
02 FILLER PIC X(14) VALUE '978-0596528120'.
02 FILLER PIC X(14) VALUE '978-1788399081'.
02 FILLER PIC X(14) VALUE '978-1788399083'.
01 TEST-ISBN REDEFINES TEST-ISBNS
OCCURS 4 TIMES
PIC X(14).
PROCEDURE DIVISION.
MAIN-PROCEDURE.
PERFORM
VARYING IX
FROM 1
BY 1
UNTIL IX > 4
DISPLAY TEST-ISBN (IX) ' ' WITH NO ADVANCING
END-DISPLAY
IF validISBN13(TEST-ISBN (IX)) = -1
DISPLAY '(bad)'
ELSE
DISPLAY '(good)'
END-IF
END-PERFORM.
GOBACK.
END PROGRAM testSubs.
******************************************************************
* Author: Jay Moseley
* Date: May 19, 2016
* Purpose: validate ISBN-13 (International Standard
* Book Number).
******************************************************************
IDENTIFICATION DIVISION.
FUNCTION-ID. validISBN13.
ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
REPOSITORY.
FUNCTION ALL INTRINSIC.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
DATA DIVISION.
FILE SECTION.
WORKING-STORAGE SECTION.
01 PASSED-SIZE PIC S9(6) COMP-5.
01 IX PIC S9(4) COMP.
01 WORK-FIELDS.
02 WF-DIGIT PIC X.
02 WF-COUNT PIC 9(2).
88 WEIGHT-1 VALUE 1, 3, 5, 7, 9, 11, 13.
88 WEIGHT-3 VALUE 2, 4, 6, 8, 10, 12.
02 WF-SUM PIC S9(8) COMP.
LINKAGE SECTION.
01 PASSED-ISBN PIC X ANY LENGTH.
01 RETURN-VALUE PIC S9.
PROCEDURE DIVISION USING PASSED-ISBN
RETURNING RETURN-VALUE.
CALL 'C$PARAMSIZE'
USING 1
GIVING PASSED-SIZE
END-CALL.
COMPUTE-CKDIGIT.
INITIALIZE WORK-FIELDS.
PERFORM
VARYING IX
FROM 1
BY 1
UNTIL IX GREATER THAN PASSED-SIZE
MOVE PASSED-ISBN (IX:1) TO WF-DIGIT
IF WF-DIGIT IS NUMERIC
ADD 1 TO WF-COUNT
IF WEIGHT-1
ADD NUMVAL(WF-DIGIT) TO WF-SUM
ELSE
COMPUTE WF-SUM = WF-SUM +
(NUMVAL(WF-DIGIT) * 3)
END-COMPUTE
END-IF
END-IF
END-PERFORM.
IF MOD(WF-SUM, 10) = 0
MOVE +0 TO RETURN-VALUE
ELSE
MOVE -1 TO RETURN-VALUE
END-IF.
GOBACK.
* - - - - - - - - - - - - - - - - - - - - - - PROGRAM EXIT POINT
END FUNCTION validISBN13.
</syntaxhighlight>
{{out}}
<pre>978-0596528126 (good)
978-0596528120 (bad)
978-1788399081 (good)
978-1788399083 (bad)
</pre>
=={{header|Cowgol}}==
<syntaxhighlight lang="cowgol">include "cowgol.coh";
sub check_isbn13(isbn: [uint8]): (r: uint8) is
var n: uint8 := 0;
r := 0;
loop
var c := [isbn];
isbn := @next isbn;
if c == 0 then break; end if;
c := c - '0';
if c <= 9 then
r := r + c;
n := n + 1;
if (n & 1) == 0 then
r := r + c * 2;
end if;
end if;
end loop;
if n == 13 and r%10 == 0 then
r := 1;
else
r := 0;
end if;
end sub;
var isbns: [uint8][] := {
"978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083"
};
var result: [uint8][] := {": bad\n", ": good\n"};
var n: uint8 := 0;
while n < @sizeof isbns loop
print(isbns[n]);
print(result[check_isbn13(isbns[n])]);
n := n + 1;
end loop;</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|D}}==
{{trans|Kotlin}}
<
bool isValidISBN13(string text) {
Line 679 ⟶ 1,195:
unittest {
assert(isValidISBN13("978-
assert(!isValidISBN13("978-
assert(isValidISBN13("978-1788399081"));
assert(!isValidISBN13("978-1788399083"));
}</
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|SysUtils,StdCtrls}}
<syntaxhighlight lang="Delphi">
function ValidateISBN(ISBN: string): boolean;
{Validate an ISBN number}
var I,N,Sum: integer;
begin
Sum:=0;
{Go througha chars, ignoring non-digits}
for I:=1 to Length(ISBN) do
if ISBN[I] in ['0'..'9'] then
begin
N:=StrToInt(ISBN[I]);
{Every other digit multiplied by 3}
if (I and 1)=1 then N:=N*3;
{Sum digits}
Sum:=Sum+N;
end;
{The sum must be an even multiple of 10}
Result:=(Sum mod 10)=0;
end;
procedure ValidateAndShow(Memo: TMemo; ISBN: string);
{Validate ISBN number and show the result}
var S: string;
begin
S:=ISBN;
if ValidateISBN(ISBN) then S:=S+' (Good)'
else S:=S+' (Bad)';
Memo.Lines.Add(S);
end;
procedure TestISBNSet(Memo: TMemo);
{Test supplied set of ISBN numbers}
begin
ValidateAndShow(Memo,'978-0596528126'); //(good)
ValidateAndShow(Memo,'978-0596528120'); //(bad)
ValidateAndShow(Memo,'978-1788399081'); //(good)
ValidateAndShow(Memo,'978-1788399083'); //(bad)
end;
</syntaxhighlight>
{{out}}
<pre>
978-0596528126 (Good)
978-0596528120 (Bad)
978-1788399081 (Good)
978-1788399083 (Bad)
</pre>
=={{header|Draco}}==
<syntaxhighlight lang="draco">proc nonrec isbn13_check(*char isbn) bool:
byte n, check, d;
char cur;
bool ok;
n := 0;
check := 0;
ok := true;
while
cur := isbn*;
isbn := isbn + 1;
ok and cur ~= '\e'
do
if n=3 then
if cur ~= '-' then ok := false fi
elif cur<'0' or cur>'9' then
ok := false
else
d := cur - '0';
if n=1 or (n>3 and n&1 = 0) then
d := d * 3;
fi;
check := check + d
fi;
n := n + 1
od;
ok and n = 14 and check%10 = 0
corp
proc nonrec test(*char isbn) void:
writeln(isbn, ": ",
if isbn13_check(isbn) then "good" else "bad" fi)
corp
proc nonrec main() void:
test("978-0596528126");
test("978-0596528120");
test("978-1788399081");
test("978-1788399083")
corp</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|EasyLang}}==
<syntaxhighlight lang="text">
func ISBN13check isbn$ .
for c$ in strchars isbn$
if c$ <> "-"
ndigs += 1
.
dig = number c$
if ndigs mod 2 = 0
dig *= 3
.
sum += dig
.
if sum mod 10 <> 0
return 0
.
return 1
.
codes$[] = [ "978-0596528126" "978-0596528120" "978-1788399081" "978-1788399083" ]
for code$ in codes$[]
if ISBN13check code$ = 1
print code$ & " is a valid ISBN"
else
print code$ & " is not a valid ISBN"
.
.
</syntaxhighlight>
{{out}}
<pre>
978-0596528126 is a valid ISBN
978-0596528120 is not a valid ISBN
978-1788399081 is a valid ISBN
978-1788399083 is not a valid ISBN
</pre>
=={{header|Excel}}==
===LAMBDA===
Binding the name '''ISBN13Check''' to the following lambda expression in the Name Manager of the Excel WorkBook:
(See [https://www.microsoft.com/en-us/research/blog/lambda-the-ultimatae-excel-worksheet-function/ LAMBDA: The ultimate Excel worksheet function])
{{Works with|Office 365 betas 2021}}
<syntaxhighlight lang="lisp">ISBN13Check
=LAMBDA(s,
LET(
ns, FILTERP(
LAMBDA(v,
NOT(ISERROR(v))
)
)(
VALUE(CHARSROW(s))
),
ixs, SEQUENCE(
1, COLUMNS(ns),
1, 1
),
0 = MOD(
SUM(
IF(0 <> MOD(ixs, 2),
INDEX(ns, ixs),
3 * INDEX(ns, ixs)
)
),
10
)
)
)</syntaxhighlight>
and also assuming the following generic bindings in the Name Manager for the WorkBook:
<syntaxhighlight lang="lisp">CHARSROW
=LAMBDA(s,
MID(s,
SEQUENCE(1, LEN(s), 1, 1),
1
)
)
FILTERP
=LAMBDA(p,
LAMBDA(xs,
FILTER(xs, p(xs))
)
)
ISDIGIT
=LAMBDA(c,
LET(
ic, CODE(c),
AND(47 < ic, 58 > ic)
)
)</syntaxhighlight>
{{Out}}
{| class="wikitable"
|-
|||style="text-align:right; font-family:serif; font-style:italic; font-size:120%;"|fx
! colspan="2" style="text-align:left; vertical-align: bottom; font-family:Arial, Helvetica, sans-serif !important;"|=ISBN13Check(A2)
|- style="text-align:center; font-family:Arial, Helvetica, sans-serif !important; background-color:#000000; color:#ffffff;"
|
| A
| B
|-
| style="text-align:center; font-family:Arial, Helvetica, sans-serif !important; background-color:#000000; color:#ffffff" | 1
| style="font-weight:bold" | Candidate string
| style="font-weight:bold" | ISBN13 checked
|-
| style="text-align:center; font-family:Arial, Helvetica, sans-serif !important; background-color:#000000; color:#ffffff" | 2
| 978-0596528126
| style="background-color:#cbcefb" | TRUE
|-
| style="text-align:center; font-family:Arial, Helvetica, sans-serif !important; background-color:#000000; color:#ffffff" | 3
| 978-0596528120
| FALSE
|-
| style="text-align:center; font-family:Arial, Helvetica, sans-serif !important; background-color:#000000; color:#ffffff" | 4
| 978-1788399081
| TRUE
|-
| style="text-align:center; font-family:Arial, Helvetica, sans-serif !important; background-color:#000000; color:#ffffff" | 5
| 978-1788399083
| FALSE
|}
=={{header|Factor}}==
<
math.functions math.parser math.vectors qw sequences
sequences.extras sets unicode ;
Line 698 ⟶ 1,446:
{ [ length 13 = ] [ [ digit? ] all? ] [ (isbn13?) ] } 1&& ;
qw{ 978-
[ dup isbn13? "good" "bad" ? "%s: %s\n" printf ] each</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|Forth}}==
The following word not only identifies correct 13 digit ISBN (and EAN) codes, but also 8 digit EAN and GTIN codes.
<syntaxhighlight lang="text">: is-digit [char] 0 - 10 u< ;
: isbn? ( a n -- f)
1- chars over + 2>r 0 1 2r> ?do
dup i c@ dup is-digit \ get length and factor, setup loop
if [char] 0 - * rot + swap 3 * 8 mod else drop drop then
-1 chars +loop drop 10 mod 0= \ now calculate checksum
;</syntaxhighlight>
{{out}}
In Forth, a "true" value is indicated by "-1".
<pre>
s" 978-0596528126" isbn? . -1 ok
s" 978-0596528120" isbn? . 0 ok
s" 978-1788399081" isbn? . -1 ok
s" 978-1788399083" isbn? . 0 ok
</pre>
=={{header|Fortran}}==
<syntaxhighlight lang="fortran">
program isbn13
implicit none
character(len=14), dimension(4), parameter :: isbns=["978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083"]
integer :: i
do i = 1, ubound(isbns, 1)
if (check_isbn13(isbns(i))) then
print*, isbns(i), " : ", "good"
else
print*, isbns(i), " : ", "bad"
end if
end do
contains
pure function check_isbn13(isbn)
character(len=*), intent(in) :: isbn
logical :: check_isbn13
integer :: summ, counter, i, digit
check_isbn13 = .false.
counter = 0
summ = 0
do i = 1, len(isbn)
if (isbn(i:i) == ' ' .or. isbn(i:i) == '-') cycle
counter = counter + 1
read(isbn(i:i), '(I1)') digit
if (modulo(counter, 2) == 0) then
summ = summ + 3*digit
else
summ = summ + digit
end if
end do
if (counter == 13 .and. modulo(summ, 10) == 0) check_isbn13 = .true.
end function check_isbn13
end program isbn13
</syntaxhighlight>
{{out}}
<pre>
978-0596528126 : good
978-0596528120 : bad
978-1788399081 : good
978-1788399083 : bad
</pre>
=={{header|FreeBASIC}}==
<
function is_num( byval c as string ) as boolean
Line 737 ⟶ 1,552:
end function
dim as string isbns(0 to 3) = { "978-
dim as uinteger i
for i = 0 to 3
Line 745 ⟶ 1,560:
print isbns(i)+": bad"
end if
next i</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|F_Sharp|F#}}==
<syntaxhighlight lang="fsharp">// ISBN13 Check Digit
open System
let parseInput (input: string) =
Seq.map(fun c -> c |> string) input |> Seq.toList |> List.map(fun x -> Int32.Parse x)
[<EntryPoint>]
let main argv =
let isbnnum = parseInput (String.filter (fun x -> x <> '-') argv.[0])
// Multiply every other digit by 3
let everyOther = List.mapi (fun i x -> if i % 2 = 0 then x * 3 else x) isbnnum
// Sum the *3 list with the original list
let sum = List.sum everyOther + List.sum isbnnum
// If the remainder of sum / 10 is 0 then it's a valid ISBN13
if sum % 10 = 0 then
printfn "%s Valid ISBN13" argv.[0]
else
printfn "%s Invalid ISBN13" argv.[0]
0</syntaxhighlight>
{{out}}
<pre>978-0596528126 Valid ISBN13
978-0596528120 Inalid ISBN13
978-1788399081 Valid ISBN13
978-1788399083 Inalid ISBN13</pre>
=={{header|Fōrmulæ}}==
{{FormulaeEntry|page=https://formulae.org/?script=examples/ISBN13_check_digit}}
'''Solution'''
[[File:Fōrmulæ - ISBN13 check digit 01.png]]
'''Test cases'''
[[File:Fōrmulæ - ISBN13 check digit 02.png]]
[[File:Fōrmulæ - ISBN13 check digit 03.png]]
=={{header|Gambas}}==
{{trans|BASIC256}}
<syntaxhighlight lang="vbnet">Public Sub Main()
Dim isbn As String[] = ["978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083", "978-2-74839-908-0", "978-2-74839-908-5", "978 1 86197 876 9"]
For n As Integer = 1 To isbn.Count
Dim sum As Integer = 0, num As Integer
Dim isbnStr As String = isbn[n]
isbnStr = Replace(isbnStr, "-", "")
isbnStr = Replace(isbnStr, " ", "")
For m As Integer = 1 To Len(isbnStr)
If m Mod 2 = 0 Then
num = 3 * CInt(Mid(isbnStr, m, 1))
Else
num = CInt(Mid(isbnStr, m, 1))
End If
sum += num
Next
If sum Mod 10 = 0 Then
Print isbn[n]; ": good"
Else
Print isbn[n]; ": bad"
End If
Next
End</syntaxhighlight>
=={{header|Go}}==
<
import (
Line 788 ⟶ 1,672:
func main() {
isbns := []string{"978-
for _, isbn := range isbns {
res := "bad"
Line 796 ⟶ 1,680:
fmt.Printf("%s: %s\n", isbn, res)
}
}</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
Line 807 ⟶ 1,691:
=={{header|Haskell}}==
<
import Text.Printf (printf)
pair :: Num a => [a] -> [(a, a)]
pair [] = []
pair xs = p (take 2 xs) : pair (drop 2 xs)
where
p ps = case ps of
(x : y : zs) -> (x, y)
(x : zs) -> (x, 0)
validIsbn13 :: String -> Bool
validIsbn13 isbn
| length (digits isbn) /= 13 = False
| otherwise = calc isbn `rem` 10 == 0
where
calc = sum . map (\(x, y) -> x + y * 3) . pair . digits
main :: IO ()
main =
mapM_
(printf "%s: Valid: %s\n" <*> (show . validIsbn13))
[ "978-0596528126",
"978-0596528120",
"978-1788399081",
"978-1788399083"
]</syntaxhighlight>
{{out}}
<pre>978-
978-
978-1788399081: Valid: True
978-1788399083: Valid: False</pre>
Line 837 ⟶ 1,727:
Or, expressed in terms of ''cycle'':
<
isISBN13 :: String -> Bool
isISBN13 =
(0 ==)
. flip rem 10
. sum
. flip
(zipWith ((*) . digitToInt) . filter isDigit)
(cycle [1, 3])
main :: IO ()
main =
mapM_
(print . ((,) <*> isISBN13)
[ "978-0596528126",
"978-0596528120",
"978-1788399081",
"978-1788399083"
]</syntaxhighlight>
{{Out}}
<pre>("978-
("978-
("978-1788399081",True)
("978-1788399083",False)</pre>
=={{header|IS-BASIC}}==
<
110 DO
120 PRINT :INPUT PROMPT "ISBN-13 code: ":IS$
Line 882 ⟶ 1,779:
330 LET SUM=SUM+VAL(ISBN$(13))
340 IF MOD(SUM,10)=0 THEN LET ISBN=-1
350 END DEF</
=={{header|J}}==
<syntaxhighlight lang="j"> D =: '0123456789'
isbn13c =: D&([ check@:i. clean)
check =: 0 = 10 | lc
lc =: [ +/@:* weight
weight =: 1 3 $~ #
clean =: ] -. a. -. [</syntaxhighlight>
{{out}}
<syntaxhighlight lang="j"> isbn13c;._1 ' 978-0596528126 978-0596528120 978-1788399081 978-1788399083'
1 0 1 0</syntaxhighlight>
=={{header|Java}}==
<syntaxhighlight lang="java">
public static void main(String[] args) {
String[] isbn13s = {
"978-0596528126",
"978-0596528120",
"978-1788399081",
"978-1788399083"
};
for (String isbn13 : isbn13s)
System.out.printf("%s %b%n", isbn13, validateISBN13(isbn13));
}
static boolean validateISBN13(String string) {
int[] digits = digits(string.strip().replace("-", ""));
return digits[12] == checksum(digits);
}
static int[] digits(String string) {
int[] digits = new int[13];
int index = 0;
for (char character : string.toCharArray()) {
if (character < '0' || character > '9')
throw new IllegalArgumentException("Invalid ISBN-13");
/* convert ascii to integer */
digits[index++] = Character.digit(character, 10);
}
return digits;
}
static int checksum(int[] digits) {
int total = 0;
int index = 0;
for (int digit : digits) {
if (index == 12) break;
if (index++ % 2 == 1) digit *= 3;
total += digit;
}
return 10 - (total % 10);
}
</syntaxhighlight>
<pre>
978-0596528126 true
978-0596528120 false
978-1788399081 true
978-1788399083 false
</pre>
<br />
An alternate demonstration
<syntaxhighlight lang="java">public static void main(){
System.out.println(isISBN13("978-0596528126"));
System.out.println(isISBN13("978-0596528120"));
System.out.println(isISBN13("978-1788399081"));
System.out.println(isISBN13("978-1788399083"));
}
public static boolean isISBN13(String in){
int pre = Integer.parseInt(in.substring(0,3));
if (pre!=978)return false;
String postStr = in.substring(4);
if (postStr.length()!=10)return false;
int post = Integer.parseInt(postStr);
int sum = 38;
for(int x = 0; x<10;x+=2)
sum += (postStr.charAt(x)-48)*3 + ((postStr.charAt(x+1)-48));
if(sum%10==0) return true;
return false;
}
</syntaxhighlight>{{out}}
<pre>
true
false
true
false
</pre>
=={{header|jq}}==
{{works with|jq}}
'''Works with gojq, the Go implementation of jq'''
<syntaxhighlight lang="jq">
def isbn_check:
def digits: tostring | explode | map( select(. >= 48 and . <= 57) | [.] | implode | tonumber);
def sum(s): reduce s as $x (null; . + $x);
digits
| . as $digits
| sum(range(0;length;2) | $digits[.]) as $one
| (3 * sum(range(1;length;2) | $digits[.])) as $two
| (($one+$two) % 10) == 0;
def testingcodes:
["978-0596528126", "978-0596528120",
"978-1788399081", "978-1788399083"];
testingcodes[]
| "\(.): \(if isbn_check then "good" else "bad" end)"
</syntaxhighlight>
{{out}}
<pre>
978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|Julia}}==
<
return sum(iseven(i) ? 3 * parse(Int, ch) : parse(Int, ch)
for (i, ch) in enumerate(replace(str, r"\D" => ""))) % 10 == 0
end
const testingcodes = ["978-
"978-1788399081", "978-1788399083"]
Line 896 ⟶ 1,909:
println(code, ": ", isbncheck(code) ? "good" : "bad")
end
</
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|K}}==
{{works with|ngn/k}}
<syntaxhighlight lang=K>digits: {x[&(x>"/")&x<":"]-"0"}
isbn13c: 0=10!+/{x*(#x)#1 3} digits@
isbn13c "978-0596528126"
1
isbn13c "978-0596528120"
0
isbn13c " 978-1788399081"
1
isbn13c "978-1788399083"
0</syntaxhighlight>
=={{header|Kotlin}}==
<syntaxhighlight lang="kotlin">
fun isValidISBN13(text: String): Boolean {
val isbn = text.replace(Regex("[- ]"), "")
Line 912 ⟶ 1,939:
.sum() % 10 == 0
}
</syntaxhighlight>
Tested using Spek
<syntaxhighlight lang="kotlin">
describe("ISBN Utilities") {
mapOf(
"978-
"978-
"978-1788399081" to true,
"978-1788399083" to false
Line 932 ⟶ 1,959:
}
}
</syntaxhighlight>
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
Line 942 ⟶ 1,969:
=={{header|langur}}==
In this example, we map to multiple functions (actually 1 no-op).
<syntaxhighlight lang="langur">
val isbn13checkdigit = fn(var s) {
s -> re/^[0-9]{13}$/ and
fold(fn{+}, map([_, fn{*3}], s2n(s))) div 10
}
val
"978-
"978-
"978-1788399081": true,
"978-1788399083": false,
}
for
val
write
writeln if(
}
</syntaxhighlight>
{{out}}
<pre>978-
978-
978-1788399081: good
978-1788399083: bad</pre>
Line 993 ⟶ 1,999:
=={{header|Lua}}==
{{trans|C}}
<
local count = 0
local sum = 0
Line 1,027 ⟶ 2,033:
function main()
test("978-
test("978-
test("978-1788399081")
test("978-1788399083")
end
main()</
{{out}}
<pre>978-
978-
978-1788399081: good
978-1788399083: bad</pre>
=={{header|Mathematica}} / {{header|Wolfram Language}}==
<syntaxhighlight lang="mathematica">ClearAll[ValidISBNQ]
ValidISBNQ[iban_String] := Module[{i},
i = StringReplace[iban, {" " -> "", "-" -> ""}];
If[StringMatchQ[i, Repeated[DigitCharacter]],
i = ToExpression /@ Characters[i];
i[[2 ;; ;; 2]] *= 3;
Mod[Total[i], 10] == 0
,
False
]
]
ValidISBNQ["978-0596528126"]
ValidISBNQ["978-0596528120"]
ValidISBNQ["978-1788399081"]
ValidISBNQ["978-1788399083"]</syntaxhighlight>
{{out}}
<pre>True
False
True
False</pre>
=={{header|MiniScript}}==
This GUI implementation is for use with [http://miniscript.org/MiniMicro Mini Micro].
<syntaxhighlight lang="miniscript">
isISBN13 = function(n)
n = n.replace("-","").replace(" ","")
s = 0
for i in range(0, n.len-1,2)
s += n[i].val
end for
for i in range(1, n.len-1,2)
s += n[i].val * 3
end for
return not (s % 10)
end function
testValues = "978-0596528126 978-0596528120 978-1788399081 978-1788399083".split(" ")
for val in testValues
print val + " " + ["bad", "good"][isISBN13(val)]
end for
</syntaxhighlight>
{{out}}
<pre>
978-0596528126 good
978-0596528120 bad
978-1788399081 good
978-1788399083 bad</pre>
=={{header|Miranda}}==
<syntaxhighlight lang="miranda">main :: [sys_message]
main = [Stdout (lay (map test tests))]
test :: [char]->[char]
test isbn = isbn ++ ": good", if isbn13 isbn
= isbn ++ ": bad", otherwise
tests :: [[char]]
tests = ["978-0596528126",
"978-0596528120",
"978-1788399081",
"978-1788399083"]
isbn13 :: [char]->bool
isbn13 str = False, if #isbn ~= 13 \/ ~and (map digit isbn)
= check mod 10 = 0, otherwise
where isbn = filter (~= '-') str
digits = map (numval.(:[])) isbn
check = sum (zipwith (*) digits (concat (repeat [1,3])))
uncurry :: (*->**->***)->(*,**)->***
uncurry f (a,b) = f a b
zipwith :: (*->**->***)->[*]->[**]->[***]
zipwith f a b = map (uncurry f) (zip2 a b)</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|Modula-2}}==
<syntaxhighlight lang="modula2">MODULE ISBN;
FROM InOut IMPORT WriteString, WriteLn;
FROM Strings IMPORT Length;
PROCEDURE validISBN(s: ARRAY OF CHAR): BOOLEAN;
VAR total, i, length: CARDINAL;
BEGIN
total := 0;
length := Length(s);
IF (length # 14) OR (s[3] # '-') THEN
RETURN FALSE;
END;
FOR i := 0 TO length-1 DO
IF i # 3 THEN
IF (s[i] < '0') OR (s[i] > '9') THEN
RETURN FALSE;
ELSIF (i < 3) AND (i MOD 2 = 1) OR (i > 3) AND (i MOD 2 = 0) THEN
total := total + 3 * (ORD(s[i]) - ORD('0'));
ELSE
total := total + ORD(s[i]) - ORD('0');
END;
END;
END;
RETURN total MOD 10 = 0;
END validISBN;
PROCEDURE check(s: ARRAY OF CHAR);
BEGIN
WriteString(s);
WriteString(': ');
IF validISBN(s) THEN
WriteString('good');
ELSE
WriteString('bad');
END;
WriteLn;
END check;
BEGIN
check('978-0596528126');
check('978-0596528120');
check('978-1788399081');
check('978-1788399083');
END ISBN.</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
Line 1,042 ⟶ 2,181:
=={{header|Nanoquery}}==
{{trans|Go}}
<
// remove any hyphens or spaces
isbn = str(isbn).replace("-","").replace(" ","")
Line 1,069 ⟶ 2,208:
end
isbns = {"978-
for isbn in isbns
res = "bad"
Line 1,077 ⟶ 2,216:
print format("%s: %s\n", isbn, res)
end</
{{out}}
<pre>978-
978-
978-1788399081: good
978-1788399083: bad</pre>
=={{header|Nim}}==
<
func is_isbn*(s: string): bool =
Line 1,098 ⟶ 2,237:
when is_main_module:
let isbns = [ "978-
"978-1788399081", "978-1788399083" ]
for isbn in isbns:
var quality: string = if is_isbn(isbn): "good" else: "bad"
echo &"{isbn}: {quality}"</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|Pascal}}==
{{works with|Extended Pascal}}
<syntaxhighlight lang="pascal">program ISBNChecksum(output);
const
codeIndexMaximum = 17;
ISBNIndexMinimum = 1;
ISBNIndexMaximum = 13;
ISBNIndexRange = ISBNIndexMaximum - ISBNIndexMinimum + 1;
type
code = string(codeIndexMaximum);
codeIndex = 1..codeIndexMaximum value 1;
decimalDigit = '0'..'9';
decimalValue = 0..9;
ISBNIndex = ISBNIndexMinimum..ISBNIndexMaximum;
ISBN = array[ISBNIndex] of decimalDigit;
{ returns the integer value represented by a character }
function numericValue(protected c: decimalDigit): decimalValue;
begin
{ in Pascal result variable bears the same name as the function }
numericValue := ord(c) - ord('0')
end;
{ determines whether an ISBN is technically valid (checksum correct) }
function isValidISBN(protected n: ISBN): Boolean;
var
sum: 0..225 value 0;
i: ISBNIndex;
begin
{ NB: in Pascal for-loop-limits are _inclusive_ }
for i := ISBNIndexMinimum to ISBNIndexMaximum do
begin
{ alternating scale factor 3^0, 3^1 based on Boolean }
sum := sum + numericValue(n[i]) * 3 pow ord(not odd(i))
end;
isValidISBN := sum mod 10 = 0
end;
{ transform '978-0-387-97649-5' into '9780387976495' }
function digits(n: code): code;
var
sourceIndex, destinationIndex: codeIndex;
begin
for sourceIndex := 1 to length(n) do
begin
if n[sourceIndex] in ['0'..'9'] then
begin
n[destinationIndex] := n[sourceIndex];
destinationIndex := destinationIndex + 1
end
end;
{ to alter a string’s length you need overwrite it completely }
digits := subStr(n, 1, destinationIndex - 1)
end;
{ data type coercion }
function asISBN(protected n: code): ISBN;
var
result: ISBN;
begin
unpack(n[1..length(n)], result, 1);
asISBN := result
end;
{ tells whether a string value contains a proper ISBN representation }
function isValidISBNString(protected hyphenatedForm: code): Boolean;
var
digitOnlyForm: code;
begin
digitOnlyForm := digits(hyphenatedForm);
{ The Extended Pascal `and_then` Boolean operator allows us }
{ to first check the length before invoking `isValidISBN`. }
isValidISBNString := (length(digitOnlyForm) = ISBNIndexRange)
and_then isValidISBN(asISBN(digitOnlyForm))
end;
{ === MAIN ============================================================= }
begin
writeLn(isValidISBNString('978-0596528126'));
writeLn(isValidISBNString('978-0596528120'));
writeLn(isValidISBNString('978-1788399081'));
writeLn(isValidISBNString('978-1788399083'))
end.</syntaxhighlight>
{{out}}
<pre>True
False
True
False</pre>
=={{header|Perl}}==
<
use warnings;
use feature 'say';
Line 1,122 ⟶ 2,354:
}
for (<978-
my($isbn,$check) = /(.*)(.)/;
my $check_d = check_digit($isbn);
say "$_ : " . ($check == $check_d ? 'Good' : "Bad check-digit $check; should be $check_d")
}</
{{out}}
<pre>978-
978-
978-1788399081 : Good
978-1788399083 : Bad check-digit 3; should be 1
Line 1,136 ⟶ 2,368:
=={{header|Phix}}==
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">procedure</span> <span style="color: #000000;">check_isbn13</span><span style="color: #0000FF;">(</span><span style="color: #004080;">string</span> <span style="color: #000000;">isbn</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">digits</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">checksum</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">0</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">w</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">1</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">isbn</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">ch</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">isbn</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;">!=</span><span style="color: #008000;">' '</span> <span style="color: #008080;">and</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;">!=</span><span style="color: #008000;">'-'</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">ch</span> <span style="color: #0000FF;">-=</span> <span style="color: #008000;">'0'</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span> <span style="color: #008080;">or</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;">></span><span style="color: #000000;">9</span> <span style="color: #008080;">then</span> <span style="color: #000000;">checksum</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">9</span> <span style="color: #008080;">exit</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #000000;">checksum</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">ch</span><span style="color: #0000FF;">*</span><span style="color: #000000;">w</span>
<span style="color: #000000;">digits</span> <span style="color: #0000FF;">+=</span> <span style="color: #000000;">1</span>
<span style="color: #000000;">w</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">4</span><span style="color: #0000FF;">-</span><span style="color: #000000;">w</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #000000;">checksum</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">remainder</span><span style="color: #0000FF;">(</span><span style="color: #000000;">checksum</span><span style="color: #0000FF;">,</span><span style="color: #000000;">10</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">string</span> <span style="color: #000000;">gb</span> <span style="color: #0000FF;">=</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">digits</span><span style="color: #0000FF;">=</span><span style="color: #000000;">13</span> <span style="color: #008080;">and</span> <span style="color: #000000;">checksum</span><span style="color: #0000FF;">=</span><span style="color: #000000;">0</span> <span style="color: #0000FF;">?</span> <span style="color: #008000;">"good"</span> <span style="color: #0000FF;">:</span> <span style="color: #008000;">"bad"</span><span style="color: #0000FF;">)</span>
<span style="color: #7060A8;">printf</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"%s: %s\n"</span><span style="color: #0000FF;">,{</span><span style="color: #000000;">isbn</span><span style="color: #0000FF;">,</span><span style="color: #000000;">gb</span><span style="color: #0000FF;">})</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">procedure</span>
<span style="color: #008080;">constant</span> <span style="color: #000000;">isbns</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{</span><span style="color: #008000;">"978-0596528126"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"978-0596528120"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"978-1788399081"</span><span style="color: #0000FF;">,</span> <span style="color: #008000;">"978-1788399083"</span><span style="color: #0000FF;">,</span>
<span style="color: #008000;">"978-2-74839-908-0"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"978-2-74839-908-5"</span><span style="color: #0000FF;">,</span><span style="color: #008000;">"978 1 86197 876 9"</span><span style="color: #0000FF;">}</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">isbns</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">do</span> <span style="color: #000000;">check_isbn13</span><span style="color: #0000FF;">(</span><span style="color: #000000;">isbns</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">])</span> <span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
Line 1,168 ⟶ 2,403:
=={{header|PicoLisp}}==
<
(let L
(make
Line 1,183 ⟶ 2,418:
(if (isbn13? A) 'ok 'fail) ) )
(quote
"978-
"978-
"978-1-86197-876-9"
"978-2-74839-908-5"
"978 1 86197 876 9" ) )</
{{out}}
<pre>
978-
978-
978-1-86197-876-9 ok
978-2-74839-908-5 fail
978 1 86197 876 9 ok
</pre>
=={{header|PL/M}}==
<syntaxhighlight lang="plm">100H:
CHECK$ISBN13: PROCEDURE (PTR) BYTE;
DECLARE PTR ADDRESS, ISBN BASED PTR BYTE;
DECLARE (I, F, T) BYTE;
F = 1;
T = 0;
DO I = 0 TO 13;
IF I = 3 THEN DO;
/* THIRD CHAR SHOULD BE '-' */
IF ISBN(I) <> '-' THEN RETURN 0;
END;
ELSE DO;
/* DIGITS MUST BE VALID */
IF ISBN(I) < '0' OR ISBN(I) > '9' THEN RETURN 0;
T = T + (ISBN(I) - '0') * F;
F = 4 - F; /* MULTIPLY BY 1 AND 3 ALTERNATELY */
END;
END;
RETURN (T MOD 10) = 0;
END CHECK$ISBN13;
/* CP/M BDOS CALL */
BDOS: PROCEDURE (FUNC, ARG);
DECLARE FUNC BYTE, ARG ADDRESS;
GO TO 5;
END BDOS;
PRINT: PROCEDURE (STR);
DECLARE STR ADDRESS;
CALL BDOS(9, STR);
END PRINT;
/* TESTS */
DECLARE TEST (4) ADDRESS;
TEST(0) = .'978-0596528126$';
TEST(1) = .'978-0596528120$';
TEST(2) = .'978-1788399081$';
TEST(3) = .'978-1788399083$';
DECLARE I BYTE;
DO I = 0 TO LAST(TEST);
CALL PRINT(TEST(I));
CALL PRINT(.': $');
IF CHECK$ISBN13(TEST(I)) THEN
CALL PRINT(.'GOOD$');
ELSE
CALL PRINT(.'BAD$');
CALL PRINT(.(13,10,'$'));
END;
CALL BDOS(0,0);
EOF</syntaxhighlight>
{{out}}
<pre>978-0596528126: GOOD
978-0596528120: BAD
978-1788399081: GOOD
978-1788399083: BAD</pre>
=={{header|PowerShell}}==
<syntaxhighlight lang="powershell">
function Get-ISBN13 {
$codes = (
"978-0596528126",
"978-0596528120",
"978-1788399081",
"978-1788399083"
)
foreach ($line in $codes) {
$sum = $null
$codeNoDash = $line.Replace("-","")
for ($i = 0; $i -lt $codeNoDash.length; $i++) {
if (($i % 2) -eq 1) {
$sum += [decimal]$codeNoDash[$i] * 3
}else {
$sum += [decimal]$codeNoDash[$i]
}
}
if (($sum % 10) -eq 0) {
Write-Host "$line Good"
}else {
Write-Host "$line Bad"
}
}
}
Get-ISBN13
</syntaxhighlight>
{{out}}
<pre>
978-0596528126 Good
978-0596528120 Bad
978-1788399081 Good
978-1788399083 Bad
</pre>
=={{header|PureBasic}}==
<syntaxhighlight lang="purebasic">Macro TestISBN13(X)
Print(X)
If IsISBN13(X) : PrintN(" good") : Else : PrintN(" bad") : EndIf
EndMacro
Procedure.b IsISBN13(ISBN13.s)
ISBN13=Left(ISBN13,3)+Mid(ISBN13,5)
If IsNAN(Val(ISBN13)) Or Len(ISBN13)<>13 : ProcedureReturn #False : EndIf
Dim ISBN.s{1}(12) : PokeS(@ISBN(),ISBN13)
For i=0 To 11 Step 2 : sum+Val(ISBN(i))+Val(ISBN(i+1))*3 : Next
sum+Val(ISBN(12))
ProcedureReturn Bool(sum%10=0)
EndProcedure
If OpenConsole()
TestISBN13("978-0596528126")
TestISBN13("978-0596528120")
TestISBN13("978-1788399081")
TestISBN13("978-1788399083")
Input()
EndIf</syntaxhighlight>
{{out}}
<pre>978-0596528126 good
978-0596528120 bad
978-1788399081 good
978-1788399083 bad
</pre>
=={{header|Python}}==
<
n = n.replace('-','').replace(' ', '')
if len(n) != 13:
Line 1,208 ⟶ 2,582:
if __name__ == '__main__':
tests = '''
978-
978-
978-1788399081
978-1788399083'''.strip().split()
for t in tests:
print(f"ISBN13 {t} validates {is_isbn13(t)}")</
{{out}}
<pre>ISBN13 978-
ISBN13 978-
ISBN13 978-1788399081 validates True
ISBN13 978-1788399083 validates False</pre>
Line 1,223 ⟶ 2,597:
Or, expressed in terms of ''itertools.cycle''
<
from itertools import cycle
# isISBN13 :: String -> Bool
def isISBN13(s):
'''True if
'''
digits = [int(c) for c in s if c.isdigit()]
return 13 == len(digits) and
0 == sum(map(
digits
)) % 10
)
# -------------------------
# main :: IO ()
def main():
'''
print('\n'.join(
repr((s, isISBN13(s))) for s
"978-0596528120",
"978-1788399081",
"978-1788399083"
]
))
# MAIN ---
if __name__ == '__main__':
main()
</syntaxhighlight>
{{Out}}
<pre>('978-
('978-
('978-1788399081', True)
('978-1788399083', False)</pre>
=={{header|Quackery}}==
<syntaxhighlight lang="quackery">[ char 0 char 9 1+ within ] is digit? ( c --> b )
[ 1 & ] is odd? ( n --> b )
[ [] swap ]'[ swap
witheach [
dup nested
unrot over do
iff [ dip join ]
else nip
] drop ] is filter ( [ --> [ )
[ 0 swap
witheach [
char->n i^ odd?
iff [ 3 * + ]
else +
] ] is checksum ( $ --> n )
[ filter digit?
dup size 13 = not
iff [ drop false ] done
checksum 10 mod 0 = ] is isbn ( $ --> b )
[ dup echo$ say ": " isbn
iff [ say "Good" ]
else [ say "Bad" ] cr ] is isbn-test ( $ --> )
$ '978-0596528126' isbn-test
$ '978-0596528120' isbn-test
$ '978-1788399081' isbn-test
$ '978-1788399083' isbn-test</syntaxhighlight>
{{out}}
<pre>
978-0596528126: Good
978-0596528120: Bad
978-1788399081: Good
978-1788399083: Bad
</pre>
=={{header|Racket}}==
<
(define (isbn13-check-digit-valid? s)
Line 1,276 ⟶ 2,699:
(module+ test
(require rackunit)
(check-true (isbn13-check-digit-valid? "978-
(check-false (isbn13-check-digit-valid? "978-
(check-true (isbn13-check-digit-valid? "978-1788399081"))
(check-false (isbn13-check-digit-valid? "978-1788399083")))</
{{out}}
Line 1,289 ⟶ 2,712:
Also test a value that has a zero check digit.
<syntaxhighlight lang="raku"
(10 - (sum (|$isbn.comb(/<[0..9]>/)) »*» (1,3)) % 10).substr: *-1
}
Line 1,300 ⟶ 2,723:
"Bad check-digit $check; should be $check-digit"
} for words <
978-
978-
978-1788399081
978-1788399083
978-2-74839-908-0
978-2-74839-908-5
>;</
{{out}}
<pre>978-
978-
978-1788399081 : Good
978-1788399083 : Bad check-digit 3; should be 1
Line 1,315 ⟶ 2,738:
978-2-74839-908-5 : Bad check-digit 5; should be 0
</pre>
=={{header|Red}}==
<syntaxhighlight lang="red">check_valid_isbn13: function [str] [
is_digit: charset [#"0" - #"9"]
remove-each i str [not pick is_digit i] ; remove non-digits
either 13 = length? str [ ; reject strings of incorrect length
sum: 0
repeat i 13 [
mul: either even? i [3] [1] ; multiplier for odd/even digits
sum: sum + (mul * to integer! to string! pick str i)
]
zero? (sum % 10) ; check if remainder mod 10 is zero
] [
false
]
]
; check given examples
foreach [str] ["978-0596528126" "978-0596528120" "978-1788399081" "978-1788399083"] [
prin str
prin " - "
print check_valid_isbn13 str
]
</syntaxhighlight>
{{out}}
<pre>
978-0596528126 - true
978-0596528120 - false
978-1788399081 - true
978-1788399083 - false
</pre>
=={{header|Refal}}==
<syntaxhighlight lang="refal">$ENTRY Go {
= <Test '978-0596528126'>
<Test '978-0596528120'>
<Test '978-1788399081'>
<Test '978-1788399083'>
};
Test {
e.X = <Prout e.X ': ' <ISBN e.X>>;
};
ISBN {
e.X, <Remove '-' e.X>: e.DS,
<CheckDigits e.DS>: {
False = Bad;
True = <ISBN1 e.DS>;
};
};
ISBN1 {
(13 s.Sum), <Mod s.Sum 10>: 0 = Good;
(13 s.Sum) e.X = Bad;
(s.N s.Sum) = Bad;
(s.N s.Sum) s.D e.X,
<+ s.N 1>: s.N1,
<Numb s.D>: s.V,
<Mod s.N 2>: {
0 = <ISBN1 (s.N1 <+ s.Sum s.V>) e.X>;
1 = <ISBN1 (s.N1 <+ s.Sum <* 3 s.V>>) e.X>;
};
e.X = <ISBN1 (0 0) e.X>;
};
Remove {
s.1 = ;
s.1 s.1 e.X = <Remove s.1 e.X>;
s.1 s.2 e.X = s.2 <Remove s.1 e.X>;
};
CheckDigits {
= True;
s.D e.X, '0123456789': e.A s.D e.B = <CheckDigits e.X>;
e.X = False;
};</syntaxhighlight>
{{out}}
<pre>978-0596528126: Good
978-0596528120: Bad
978-1788399081: Good
978-1788399083: Bad</pre>
=={{header|REXX}}==
A couple of additional checks were made to verify a correct length, and also that the ISBN-13 code is all numerics (with optional minus signs).
<
parse arg $ /*obtain optional arguments from the CL*/
if $='' | if $="," then $= '978-
@ISBN= "ISBN─13 code isn't" /*a literal used when displaying msgs. */
/* [↓] remove all minuses from X code.*/
Line 1,336 ⟶ 2,847:
if right(sum, 1)==0 then say ' ISBN-13 code ' x " is valid."
else say ' ISBN-13 code ' x " isn't valid."
end /*j*/ /*stick a fork in it, we're all done. */</
{{out|output|text= when using the four default inputs:}}
<pre>
Line 1,343 ⟶ 2,854:
ISBN-13 code 9781788399081 is valid.
ISBN-13 code 9781788399083 isn't valid.
</pre>
=={{header|Ring}}==
<syntaxhighlight lang="ring">
load "stdlib.ring"
isbn = ["978-0596528126","978-0596528120", "978-1788399081", "978-1788399083","978-2-74839-908-0","978-2-74839-908-5","978 1 86197 876 9"]
for n = 1 to len(isbn)
sum = 0
isbnStr = isbn[n]
isbnStr = substr(isbnStr,"-","")
isbnStr = substr(isbnStr," ","")
for m = 1 to len(isbnStr)
if m%2 = 0
num = 3*number(substr(isbnStr,m,1))
sum = sum + num
else
num = number(substr(isbnStr,m,1))
sum = sum + num
ok
next
if sum%10 = 0
see "" + isbn[n] + ": true" + nl
else
see "" + isbn[n] + ": bad" + nl
ok
next
</syntaxhighlight>
Output:
<pre>
978-0596528126: true
978-0596528120: bad
978-1788399081: true
978-1788399083: bad
978-2-74839-908-0: true
978-2-74839-908-5: bad
978 1 86197 876 9: true
</pre>
=={{header|RPL}}==
{{works with|Halcyon Calc|4.2.7}}
≪ → isbn
≪ 0 1 CF
1 isbn SIZE FOR j
IF "0123456789" isbn j DUP SUB POS THEN
LAST 1 -
IF 1 FS?C THEN 3 * ELSE 1 SF END
+
END
NEXT
≫
10 MOD NOT
≫
'ISBN?' STO
≪ { "978-0596528126" "978-0596528120" "978-1788399081" "978-1788399083" } → tests
≪ 1 tests SIZE FOR j tests GET ISBN? NEXT ≫
≫ EVAL
{{out}}
<pre>
4: 1
3: 0
2: 1
1: 0
</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">def validISBN13?(str)
cleaned = str.delete("^0-9").chars
return false unless cleaned.size == 13
cleaned.each_slice(2).sum{|d1, d2| d1.to_i + 3*d2.to_i }.remainder(10) == 0
end
isbns = ["978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083"]
isbns.each{|isbn| puts "#{isbn}: #{validISBN13?(isbn)}" }
</syntaxhighlight>{{out}}
<pre>978-0596528126: true
978-0596528120: false
978-1788399081: true
978-1788399083: false
</pre>
=={{header|Rust}}==
<
let isbns = ["978-
isbns.iter().for_each(|isbn| println!("{}: {}", isbn, check_isbn(isbn)));
}
Line 1,360 ⟶ 2,951:
checksum % 10 == 0
}
</syntaxhighlight>
{{out}}
<pre>
978-
978-
978-1788399081: true
978-1788399083: false
</pre>
=={{header|Seed7}}==
<syntaxhighlight lang="seed7">$ include "seed7_05.s7i";
const func boolean: isISBN13 (in var string: input) is func
result
var boolean: isbn is FALSE;
local
var char: c is ' ';
var integer: digit is 0;
var integer: i is 1;
var integer: sum is 0;
begin
input := replace(input, " ", "");
input := replace(input, "-", "");
if length(input) = 13 then
for c range input do
digit := ord(c) - 48;
if not odd(i) then
digit *:= 3;
end if;
sum +:= digit;
incr(i);
end for;
isbn := sum rem 10 = 0;
end if;
end func;
const proc: main is func
local
var string: str is "";
begin
for str range [] ("978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083") do
writeln(str <& ": " <& isISBN13(str));
end for;
end func;</syntaxhighlight>
{{out}}
<pre>
978-0596528126: TRUE
978-0596528120: FALSE
978-1788399081: TRUE
978-1788399083: FALSE
</pre>
=={{header|SETL}}==
<syntaxhighlight lang="setl">program isbn13;
loop for test in [
"978-0596528126", "978-0596528120",
"978-1788399081", "978-1788399083"
] do
print(test + if valid_isbn13 test then ": good" else ": bad" end);
end loop;
op valid_isbn13(isbn);
if #isbn /= 14
or isbn(4) /= '-'
or exists c in isbn | not c in "0123456789-" then
return false;
end if;
m := 3;
loop for ch in isbn | ch in "0123456789" do
s +:= val ch * (m := 4 - m);
end loop;
return s mod 10 = 0;
end op;
end program;</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|Standard ML}}==
===Easy to read version===
<syntaxhighlight lang="sml">(* these type decorations are optional, you could just as well put:
fun isValidISBN s =
*)
fun isValidISBN (s : string) : bool =
let
val digits = List.filter Char.isDigit (explode s)
val nums = map (fn x => ord x - ord #"0") digits
val len = length nums
fun sumISBN [] = raise Domain
| sumISBN [x] = x
| sumISBN (x1::x2::xs) = x1 + 3*x2 + sumISBN xs
in
len = 13 andalso sumISBN nums mod 10 = 0
end
val test = ["978-1734314502", "978-1734314509",
"978-1788399081", "978-1788399083"]
fun printTest (s : string) : unit =
(print s; print (if isValidISBN s then ": good\n" else ": bad\n"))
fun main () = app printTest test</syntaxhighlight>
===Original version===
<syntaxhighlight lang="sml">let
fun check (c, p as (m, n)) =
if Char.isDigit c then
(not m, (if m then 3 * (ord c - 48) else ord c - 48) + n)
else
p
in
fun checkISBN s =
Int.rem (#2 (CharVector.foldl check (false, 0) s), 10) = 0
end
val test = ["978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083"]
val () = (print
o concat
o map (fn s => s ^ (if checkISBN s then ": good\n" else ": bad\n"))) test</syntaxhighlight>
{{out}}
<pre>978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad</pre>
=={{header|Swift}}==
<
guard !isbn.isEmpty else {
return false
Line 1,386 ⟶ 3,095:
let cases = [
"978-
"978-
"978-1788399081",
"978-1788399083"
Line 1,394 ⟶ 3,103:
for isbn in cases {
print("\(isbn) => \(checkISBN(isbn: isbn) ? "good" : "bad")")
}</
{{out}}
<pre>978-
978-
978-1788399081 => good
978-1788399083 => bad</pre>
=={{header|Tcl}}==
<syntaxhighlight lang="tcl">
proc validISBN13 code {
regsub -all {\D} $code "" code ;# remove non-digits
if {[string length $code] == 13} {
set sum 0
set fac 1
foreach digit [split $code ""] {
set sum [expr {$sum + $digit * $fac}]
set fac [expr {$fac == 1? 3: 1}]
}
if {$sum % 10 == 0} {return true}
}
return false
}
foreach test {
978-0596528126
978-0596528120
978-1788399081
978-1788399083
} {puts $test:[validISBN13 $test]}
</syntaxhighlight>
{{out}}
<pre>978-0596528126:true
978-0596528120:false
978-1788399081:true
978-1788399083:false</pre>
Simpler variant, using two loop vars and constant factors; same output:
<syntaxhighlight lang="tcl">
proc validISBN13 code {
regsub -all {\D} $code "" code ;# remove non-digits
if {[string length $code] == 13} {
set sum 0
foreach {d1 d2} [split $code ""] {
if {$d2 eq ""} {set d2 0} ;# last round
set sum [expr {$sum + $d1 + $d2 * 3}]
}
if {$sum % 10 == 0} {return true}
}
return false
}
</syntaxhighlight>
=={{header|uBasic/4tH}}==
{{works with|version 3.64.0}}
<syntaxhighlight lang="text">a := "978-0596528126"
Print Show(a), Show (Iif (Func(_IsISBN (a)), "good", "bad"))
a := "978-0596528120"
Print Show(a), Show (Iif (Func(_IsISBN (a)), "good", "bad"))
a := "978-1788399081"
Print Show(a), Show (Iif (Func(_IsISBN (a)), "good", "bad"))
a := "978-1788399083"
Print Show(a), Show (Iif (Func(_IsISBN (a)), "good", "bad"))
End
_IsISBN
Param (1)
Local (4)
c@ = 0 : e@ = 1 ' set sum and multiplier
For b@ = Len (a@) - 1 To 0 Step -1 ' scan string in reverse
d@ = Peek(a@, b@) - Ord ("0") ' get character
If ((d@ < 0) + (d@ > 9)) = 0 Then c@ = c@ + (d@ * e@)
e@ = (e@ * 3) % 8 ' evaluate character, change multiplier
Next
Return ((c@ % 10) = 0) ' modulus 10 must be zero</syntaxhighlight>
{{out}}
<pre>978-0596528126 good
978-0596528120 bad
978-1788399081 good
978-1788399083 bad
0 OK, 0:339</pre>
=={{header|UNIX Shell}}==
{{works with|Bourne Again Shell}}
<syntaxhighlight lang="sh">check_isbn13 () {
local i n t
n=${1//[^0-9]/}
t=0
for ((i=0; i<${#n}; ++i )); do
(( t += ${n:i:1}*(1 + ((i&1)<<1)) ))
done
(( 0 == t % 10 ))
}
for isbn in 978-0596528126 978-0596528120 978-1788399081 978-1788399083; do
printf '%s: ' "$isbn"
if check_isbn13 "$isbn"; then
printf '%s\n' OK
else
printf '%s\n' 'NOT OK'
fi
done</syntaxhighlight>
{{Out}}
<pre>978-0596528126: OK
978-0596528120: NOT OK
978-1788399081: OK
978-1788399083: NOT OK</pre>
=={{header|Visual Basic .NET}}==
{{trans|C#}}
<syntaxhighlight lang="vbnet">Module Module1
Function CheckISBN13(code As String) As Boolean
code = code.Replace("-", "").Replace(" ", "")
If code.Length <> 13 Then
Return False
End If
Dim sum = 0
For Each i_d In code.Select(Function(digit, index) (index, digit))
Dim index = i_d.index
Dim digit = i_d.digit
If Char.IsDigit(digit) Then
sum += (Asc(digit) - Asc("0")) * If(index Mod 2 = 0, 1, 3)
Else
Return False
End If
Next
Return sum Mod 10 = 0
End Function
Sub Main()
Console.WriteLine(CheckISBN13("978-0596528126"))
Console.WriteLine(CheckISBN13("978-0596528120"))
Console.WriteLine(CheckISBN13("978-1788399081"))
Console.WriteLine(CheckISBN13("978-1788399083"))
End Sub
End Module</syntaxhighlight>
{{out}}
<pre>True
False
True
False</pre>
=={{header|V (Vlang)}}==
{{trans|Go}}
<syntaxhighlight lang="v (vlang)">
fn check_isbn13(isbn13 string) bool {
// remove any hyphens or spaces
isbn := isbn13.replace('-','').replace(' ','')
// check length == 13
le := isbn.len
if le != 13 {
return false
}
// check only contains digits and calculate weighted sum
mut sum := 0
for i, c in isbn.split('') {
if c.int() < '0'.int() || c.int() > '9'.int() {
return false
}
if i%2 == 0 {
sum += c.int() - '0'.int()
} else {
sum += 3 * (c.int() - '0'.int())
}
}
return sum%10 == 0
}
fn main() {
isbns := ["978-0596528126", "978-0596528120", "978-1788399081", "978-1788399083"]
for isbn in isbns {
mut res := "bad"
if check_isbn13(isbn) {
res = "good"
}
println("$isbn: $res")
}
}</syntaxhighlight>
{{out}}
<pre>
978-0596528126: good
978-0596528120: bad
978-1788399081: good
978-1788399083: bad
</pre>
=={{header|Wren}}==
<
var cps = s.codePoints
var digits = []
Line 1,422 ⟶ 3,319:
}
var tests = ["978-
for (test in tests) {
System.print("%(test) -> %(isbn13.call(test) ? "good" : "bad")")
}</
{{out}}
<pre>
978-
978-
978-1788399081 -> good
978-1788399083 -> bad
Line 1,436 ⟶ 3,333:
=={{header|XPL0}}==
<
proc ISBN13(Str); \Show if International Standard Book Number is good
Line 1,456 ⟶ 3,353:
];
[ISBN13("978-
ISBN13("978-
ISBN13("978-1788399081");
ISBN13("978-1788399083");
ISBN13("978-1-59327-220-3");
ISBN13("978-178839918");
]</
{{out}}
<pre>
978-
978-
978-1788399081: good
978-1788399083: bad
Line 1,475 ⟶ 3,372:
=={{header|zkl}}==
<
var [const] one3=("13"*6 + 1).split("").apply("toInt"); // examine 13 digits
// one3=("13"*6) if you want to calculate what the check digit should be
one3.zipWith('*,isbn - " -").sum(0) % 10 == 0
}</
<
#<<<"
978-
978-
978-1788399081
978-1788399083
Line 1,490 ⟶ 3,387:
#<<<
foreach isbn in (isbns)
{ println(isbn.strip()," ",ISBN13_check(isbn) and " Good" or " Bad") }</
{{out}}
<pre>
978-
978-
978-1788399081 Good
978-1788399083 Bad
|