johngg@shiraz:~/perl > perl -Mstrict -Mwarnings -E '
my $str = q{abc  };
my $pck = pack q{Z*}, $str;
say sprintf q{%02x}, ord for split m{}, $pck;
say q{-} x 5;
say sprintf q{%02x}, ord for split m{}, unpack q{Z*}, $pck;'
61
62
63
20
20
00
-----
61
62
63
20
20

##</code><code>##

johngg@shiraz:~/perl > perl -Mstrict -Mwarnings -E '
my $str = q{abc  };
my $pck = pack q{a10}, $str;
say qq{unpack A*:};
say sprintf q{     %02x}, ord
   for split m{}, unpack q{A*}, $pck;
say qq{unpack Z*:};
say sprintf q{     %02x}, ord
   for split m{}, unpack q{Z*}, $pck;
say qq{unpack a*:};
say sprintf q{     %02x}, ord
   for split m{}, unpack q{a*}, $pck;'
unpack A*:
     61
     62
     63
unpack Z*:
     61
     62
     63
     20
     20
unpack a*:
     61
     62
     63
     20
     20
     00
     00
     00
     00
     00