25 Aug
2009
25 Aug
'09
2:11 p.m.
On Sat, 22 Aug 2009, Bulat Ziganshin wrote:
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
This needs quadratic time with respect to the number of digits, doesn't it? If (show . length) is not fast enough, I would try to catch the magnitude by repeated squaring of 10. If you have found a 'k' with 10^(2^k) <= n < 10^(2^(k+1)) then you can start to find the exact number of digits with bisection.