David House wrote:
When you want to do manipulation on the digits of a number like this,
normally the easiest thing to do is to convert it to a string, use
list manipulation functions, then convert back to an integer.
For example:
Prelude> (read . reverse . show) 17
71
swapInteger :: Integer -> Integer
swapInteger x = swapInteger' (x,0)
swapInteger' :: (Integer,Integer) -> Integer
swapInteger' (0,x) = x
swapInteger' (remaining, result) = swapInteger' $ (remaining',
result*10 + result')
where (remaining', result') = remaining `divMod` 10
Works for all positive integer, and doesn't hassle around with
converting it to a string.
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