ISBN13 check digit: Difference between revisions
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</pre> |
</pre> |
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=={{header|Haskell}}== |
=={{header|Haskell}}== |
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Uses Data.List.Split library: https://hackage.haskell.org/package/split-0.2.3.4/docs/Data-List-Split.html |
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<lang haskell> |
<lang haskell> |
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import Data.List.Split (chunksOf) |
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import Data.Char (isDigit, digitToInt) |
import Data.Char (isDigit, digitToInt) |
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import Control.Monad (forM_) |
import Control.Monad (forM_) |
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testISBNs :: [String] |
testISBNs :: [String] |
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testISBNs = ["978-1734314502" , "978-1734314509", "978-1788399081", "978-1788399083"] |
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testISBNs = |
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[ "978-1734314502" -- good |
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pair :: Num a => [a] -> [(a, a)] |
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, "978-1734314509" -- bad |
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pair [] = [] |
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, "978-1788399081" -- good |
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pair xs = p' (take 2 xs) : pair (drop 2 xs) |
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, "978-1788399083" -- bad |
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where p' ps = case ps of (x:y:zs) -> (x,y) |
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] |
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| ⚫ | |||
validIsbn13 :: String -> Bool |
validIsbn13 :: String -> Bool |
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| otherwise = calc isbn `rem` 10 == 0 |
| otherwise = calc isbn `rem` 10 == 0 |
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where digits = map digitToInt . filter isDigit |
where digits = map digitToInt . filter isDigit |
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calc = foldl (\a |
calc = foldl (\a (x, y) -> x + y * 3 + a) 0 . pair . digits |
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| ⚫ | |||
else head b + a) 0 . chunksOf 2 . digits |
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main :: IO () |
main :: IO () |
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978-1788399083: Valid: False |
978-1788399083: Valid: False |
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</pre> |
</pre> |
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=={{header|Julia}}== |
=={{header|Julia}}== |
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<lang julia>function isbncheck(str) |
<lang julia>function isbncheck(str) |
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