Here's a common recipe for converting IP addresses in dotted-quad notation (192.168.0.1 for example) to an integer number and converting back again. I always seem to lose this recipe when I need it so I'll jot it down here. This is useful for storing an IP address, subnet, or subnet mask in a database as you can store it in a 4 byte integer field rather than a 15 byte char, a savings of 11 bytes per record (by MySQL's data types).

   sub quad2int
   {
      return unpack("N",pack("C4",split('\.',$_[0])));
   }

   sub int2quad
   {
      return join('.',unpack('C4', pack("N", $_[0])));
   }
	

I yanked this code from the fantastic Perl module Net::Netmask by David Muir Sharnoff