ISBN13 check digit: Difference between revisions

=={{header|Action!}}==

{{libheader|Action! Tool Kit}}

<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("978-1734314502")

Test("978-1734314509")

Test("978-1788399081")

Test("978-1788399083")

RETURN</lang>

{{out}}

[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/ISBN13_check_digit.png Screenshot from Atari 8-bit computer]

<pre>

978-1734314502 is correct

978-1734314509 is incorrect

978-1788399081 is correct

978-1788399083 is incorrect

</pre>