int ip2long ( string $ip_address )
The function ip2long() generates an IPv4 Internet network address from its Internet standard format (dotted string) representation. ip2long() will also work with non-complete IP addresses. Read » http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/libs/commtrf2/inet_addr.htm for more info.
Returns the IPv4 address or FALSE if ip_address is invalid.