my $string = "abc12defghi\013jkl";
(my $copy = $string) =~ s/([^[:print:]])/sprintf " (0x%02x) ", ord $1/
+ge;
print $copy;
[download]

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

package StringInspector;

use Hash::Util qw(lock_keys);
use strict;

sub new {
    my $self = {};
    $self->{SUSPECT} = "";
    $self->{BYTES_IN_ROW} = 10;
    $self->{COLUMNS_BETWEEN_PANES} = 5;
    bless $self;
    lock_keys(%{$self});
    return $self;
}

sub inspect {
    my ($self, $string) = @_;
    $self->{SUSPECT} = $string;
}

sub bytes_in_row {
    my $self = shift;
    if (@_) {
        $self->{BYTES_IN_ROW} = shift;
    }
    return $self->{BYTES_IN_ROW};
}

sub columns_between_panes {
    my $self = shift;
    if (@_) {
        $self->{COLUMNS_BETWEEN_PANES} = shift;
    }
    return $self->{COLUMNS_BETWEEN_PANES};
}

sub display {
    use bytes;
    my $self = shift;
    for (my $index = 0; $index <= length $self->{SUSPECT}; $index += $
+self->{BYTES_IN_ROW}) {
        my ($numbers, $chars) = ("", "");
        foreach my $this_char (split(//, substr($self->{SUSPECT}, $ind
+ex, $self->{BYTES_IN_ROW}))) {
            my $ascii = ord($this_char);
            $numbers .= sprintf("0x%0x  ", $ascii);
            $chars .= (($ascii >= 32) and ($ascii <= 126)) ? $this_cha
+r : "."; 
        }
        print $numbers;
        print " " x (6 * $self->{BYTES_IN_ROW} - length $numbers);
        print " " x $self->{COLUMNS_BETWEEN_PANES};
        print $chars;
        print "\n";
    }
}

1;


testing code:
use StringInspector;
use strict;
my $inspector = new StringInspector;
$inspector->bytes_in_row(3);
$inspector->columns_between_panes(40);
$inspector->inspect("abcdefghi" . chr(400) ."jkl");
$inspector->display();
[download]