       Re: Number of Differing Digits & Another Problem (want

• To: mathgroup at smc.vnet.net
• Subject: [mg76331] Re: [mg76310] Number of Differing Digits & Another Problem (want
• From: Carl Woll <carlw at wolfram.com>
• Date: Sun, 20 May 2007 02:19:02 -0400 (EDT)
• References: <200705190845.EAA21281@smc.vnet.net>

VenDiddy at gmail.com wrote:

>I just purchased a copy of Mathematica and I've been learning it for
>about a week now. You can expect that I will be posting a lot of
>questions. One thing I've noticed is that there are so many different
>ways to do the same thing!
>
>Here is a function I came up with that calculates how many binary
>digits two numbers differ in:
>
>BitDifferences[a_, b_, n_] :=
> Count[Equal @@@
>   Thread[{IntegerDigits[a, 2, n], IntegerDigits[b, 2, n]}], True]
>
>For example 5 = 101 differs from 6 = 111 by one digit (the middle
>digit).
>
>I want to see how you would do it so I can broaden my Mathematica
>perspective.
>
>Thanks.
>
>
>
I would use BitXor and DigitCount as follows:

bit2[a_, b_] := DigitCount[ BitXor[a, b], 2, 1]

Carl Woll
Wolfram Research

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