$x = "one\0two\0";
$b = pack "p", $x;                  # pointer to "one"
$b .= pack 'I', 4 + unpack 'I', $b; # pointer to "two" = substr($x, 4)
printf "length: %i\n", length $b;
printf "%i %i\n", unpack "II", $b;
printf "%s\n", $_ for unpack "pp", $b;

##</code><code>##

printf "%s\n", $_ for unpack "P2P2", $b;