Re: comparing two binary numbers

----- Original Message ----- 
From: ""Johnson Lau"" <[email protected]>
Newsgroups: perl.beginners
To: <[email protected]>
Sent: Sunday, May 11, 2008 1:09 AM
Subject: comparing two binary numbers


> Dear all,
>
> I need to compare two binary numbers and need perl to return the
> number of matching bits.
>
> For example:
>
> $aaa = "10111100";
> $bbb = "00101100";
>
> In this case, the number of matching bits is 6.
>
> I know I could split the strings and compare the bits one by one.
> However, is there any faster functions for this? I need to compare
> millions of such strings with 1000 bits for each.
>
> Thanks a lot!!
>
> Johnson Lau

After reading the others' replies, I believe this xor operation will do what 
you want;

#!/usr/bin/perl
use strict;
use warnings;

my $aaa = "10111100";
my $bbb = "00101100";

my $same = ($aaa ^ $bbb) =~ tr/\0//;

print $same;


Chris