[Haskell-cafe] How to calculate de number of digits of an integer? (was: Is logBase right?)

[José Prous]

It looks like length . show is faster

Prelude Control.Arrow> let numDigits n = length $ show n
Prelude Control.Arrow> let digits = iterate (`div` 10) >>> takeWhile (>0)
>>> length
Prelude Control.Arrow> let n=2^1000000
Prelude Control.Arrow> :set +s
Prelude Control.Arrow> numDigits n
301030
(0.39 secs, 23001616 bytes)
Prelude Control.Arrow> digits n
301030
(51.06 secs, 19635437248 bytes)


2009/8/22 Bulat Ziganshin <bulat.ziganshin at gmail.com>

> Hello Roberto,
>
> Saturday, August 22, 2009, 9:19:26 PM, you wrote:
>
> > I want to calculate the number of digits of a positive integer. I was
>
> fastest way
>
> digits = iterate (`div` 10) >>> takeWhile (>0) >>> length
>
>
> --
> Best regards,
>  Bulat                            mailto:Bulat.Ziganshin at gmail.com
>
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