ISBN13 check digit: Difference between revisions

=={{header|Ruby}}==

{{trans|C#}}

<lang ruby>def checkISBN13(code)

length = 0

sum = 0

code.split('').each { |c|

if '0' <= c and c <= '9' then

if length % 2 == 0 then

sum = sum + 1 * (c.ord - '0'.ord)

else

sum = sum + 3 * (c.ord - '0'.ord)

end

length = length + 1

end

}

if length != 13 then

return false

end

return sum % 10 == 0

end

def main

puts checkISBN13("978-1734314502")

puts checkISBN13("978-1734314509")

puts checkISBN13("978-1788399081")

puts checkISBN13("978-1788399083")

end

main()</lang>

{{out}}

<pre>true

false

true

false</pre>