Re: comparing two binary numbers

"Johnson Lau" schreef:

> 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.

perl -Mstrict -Mwarnings -le'
    my $b1 = "10111100";
    my $b2 = "00101100";
    $b2 =~ tr/01/10/;

    my $n = ($b1 & $b2) =~ tr/0/0/;
    print $n;
'
6

To derive the length, a prepared hash (with 256 keys) will be faster.



perl -Mstrict -Mwarnings -le'
    my $b1 = oct "0b" . "10111100";
    my $b2 = oct "0b" . "00101100";

    my $n = sprintf("%08b", $b1 ^ $b2) =~ tr/0/0/;
    print $n;
'

To derive the length, a prepared array (with 256 elements) is much
faster.

-- 
Affijn, Ruud

"Gewoon is een tijger."