or download this
use strict;
use warnings;
...
print "Network (32 bits) pack/unpack: ", unpack ('N', pack ('N', -1)),
+ "\n";
print "Long pack/unpack: ", unpack ('l', pack ('l', -1)), "\n";
print "Network (cvt) pack/unpack: ", unpack ('s', pack ('s', unpack ('
+n', pack ('n', -1)))), "\n";