my $len = unpack 'C/a*', $packed;
my ($data) = unpack 'C/a*', $packed;

##</code><code>##

print join ":", unpack 'CXC/a*', $packed;

##</code><code>##

19:the quick brown fox

##</code><code>##

print join ":", unpack 'C@0C/a*', $packed;

##</code><code>##

print join ":", unpack 'C@C/a*X15a5x7a*', $packed;

##</code><code>##

19:the quick brown fox:quick:fox