IP4toInt32.rb

=begin

Take the following IPv4 address: 128.32.10.1 This address has 4 octets where
each octet is a single byte (or 8 bits).

1st octet 128 has the binary representation: 10000000
2nd octet 32 has the binary representation: 00100000
3rd octet 10 has the binary representation: 00001010
4th octet 1 has the binary representation: 00000001
So 128.32.10.1 == 10000000.00100000.00001010.00000001

Because the above IP address has 32 bits, we can represent it as the 32 bit
number: 2149583361.

Write a function ip_to_int32(ip) ( JS: ipToInt32(ip) ) that takes an IPv4
address and returns a 32 bit number.

  ip_to_int32("128.32.10.1") => 2149583361

=end

# My Solution
def ip_to_int32(ip)
  ip = ip.split(".").map {|x| sprintf '%08d', x.to_i.to_s(2)}.join.to_i(2)
end

# Better Solution
require 'ipaddr'

def ip_to_int32(ip)
  x = IPAddr.new(ip).to_i
end

# Another Solution
def ip_to_int32(ip)
  ip.split( '.' ).reduce( 0 ) { |total, p| total * 256 + p.to_i }
end