use strict;
use warnings;

use feature    qw{ say };
use List::Util qw{ max };

my $string   = qq{abc\n};
my $packed   = pack   q{A*}, $string;
my $unpacked = unpack q{A*}, $packed;

say
   $string eq $packed
   ? q{OK - original and packed are the same}
   : q{Not OK - original and packed differ};

sideBySide( $string, $packed );

say
   $string eq $unpacked
   ? q{OK - original and unpacked are the same}
   : q{Not OK - original and unpacked differ};

sideBySide( $string, $unpacked );

say q{=} x 50;

$string  .= qq{def\n};
$packed   = pack   q{A*}, $string;
$unpacked = unpack q{A*}, $packed;

say
   $string eq $packed
   ? q{OK - original and packed are the same}
   : q{Not OK - original and packed differ};

sideBySide( $string, $packed );

say
   $string eq $unpacked
   ? q{OK - original and unpacked are the same}
   : q{Not OK - original and unpacked differ};

sideBySide( $string, $unpacked );

sub sideBySide
{
    my( $original, $modified ) = @_;

    my @origChars = map { sprintf q{%#02x}, ord } split m{}, $original;
    my @modChars  = map { sprintf q{%#02x}, ord } split m{}, $modified;
    my $nRows     = max scalar( @origChars ), scalar( @modChars );

    for ( 1 .. $nRows )
    {
        printf qq{%8s%8s\n},
           scalar @origChars ? shift @origChars : q{},
           scalar @modChars  ? shift @modChars  : q{};
    }
}