map $_ // '[undef]'

##</code><code>##

map defined($_) ? $_ : '[undef]'

##</code><code>##

for my $nic (networkInfo()) {
    print "Device: $nic->{device} has IP Address $nic->{ip}\n" .
        "\tMask: $nic->{mask}\n" .
        "\tBroadcast: $nic->{bcast}\n";
    print "Device: $nic->{device} also IPv6 address $nic->{ip6}\n"
        if defined($nic->{device});
}