Select Code to Download

my $x = '255.0.0.0';
print "$x is a valid mask!\n" if validateMask($x);
...
  return 1;                             # return 1 if everything is ok
+ay
}

11111111000000000000000000000000 is a valid mask!

print "255.0.0.0 is a valid mask!\n" if validateMask('255.0.0.0');

Modification of a read-only value attempted at ./idnopheq.pl line 5.

my $mask = shift;

sub validateMask {
  $_ = shift;
  return unless /^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/;
  unpack('B32', pack('C4', split /\./)) =~ /01/ ? undef : 1;
}