http://www.perlmonks.org?node_id=1015618


in reply to Re^2: Efficient bit counting with a twist.
in thread Efficient bit counting with a twist.

Thanks for the explanation. I wasn't getting his solution at first until I saw your description of the steps. For those who need a little more (as I did): perlpacktut. It's funny, I'm sure we've all read that document numerous times, and yet before this I never noticed the % feature.

Update: Fixed perlunpacktut: sb perlpacktut.


Dave

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Re^4: Efficient bit counting with a twist.
by AnomalousMonk (Archbishop) on Jan 28, 2013 at 09:01 UTC

    The summing function is discussed in the Doing Sums section of perlpacktut (not perlunpacktut, which does not exist) and in unpack, although it must be admitted that examples of counted-field summation in both these sources are a bit rare.

Re^4: Efficient bit counting with a twist.
by BrowserUk (Patriarch) on Jan 28, 2013 at 12:11 UTC
    It's funny, I'm sure we've all read that document numerous times, and yet before this I never noticed the % feature.

    I've read it many times, and use the bit-counting form regularly; but always as '%32b*'.

    As soon as I half read AnomalousMonk's post, the significance/simplicity of using a count rather than '*' became immediately obvious to me, and I physically blushed red in the realisation.

    The only factor that slightly lessened my embarrassment was that I was not the only one who missed it. But only slightly :)


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