ISBN13 check digit: Difference between revisions

=={{header|Quackery}}==

<lang quackery>[ char 0 char 9 1+ within ] is digit? ( c --> b )

[ 1 & ] is odd? ( n --> b )

[ [] swap ]'[ swap

witheach [

tuck 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 ( $ --> )

$ '978-1734314502' isbn-test

$ '978-1734314509' isbn-test

$ '978-1788399081' isbn-test

$ '978-1788399083' isbn-test</lang>

{{out}}

<pre>

978-1734314502: Good

978-1734314509: Bad

978-1788399081: Good

978-1788399083: Bad

</pre>