use Socket;
use URI;

my $url = 'http://www.mydomain.com';

my $uri = URI->new( $url );
my $ip_addr = gethostbyname( $uri->host );
$ip_addr = inet_ntoa( $ip_addr );

if ( $uri->host eq $ip_addr ) {

    #... Creatures evolve, code does stuff

}
[download]

The advantage that this method of employing the URI module over a simple regular expression is the correct handling of more complex URLs (which may incorporate username and password authentication details in the form of scheme://username:password@host:port/) and validation of IP addresses.

perl -e 'print+unpack("N",pack("B32","00000000000000000000000111001001")),"\n"'

There really isn't any need for that socket stuff.

use URI;
my $url = 'http://foo.bar.com';
my $uri = new URI($url);

if( $uri->host =~ /[a-zA-Z\-]/ ) { # or /[^\d\.]/
#    it's an IP dag-nabbit
}
[download]

____________________________________________________
** The Third rule of perl club is a statement of fact: pod is sexy.

Agreed, this approach does simplify things somewhat - The incorporation of the Socket stuff does however have the advantage of ensuring that the IP address (hostname) extracted is valid.

 

perl -e 'print+unpack("N",pack("B32","00000000000000000000000111001010")),"\n"'