This is definitely the way to go. ++

Based upon your requirements I would do something like this. You might also add a hash of all valid TLD combinations, but that might be what you want to get.

#!/usr/bin/perl -w
   
use strict;
   
while( my $url = <DATA> )
   {  chomp($url);
      my @Url = split(/\./,$url);
      if ( length($Url[$#Url]) == 3 )
          {   print "$url:\t\tTLD is '".$Url[$#Url]."'\n";
          }
      else
          {   print "$url:\t\tTLD is '".$Url[$#Url-1].".".$Url[$#Url].
+"'\n";
          }
   }
   
   1;
   
   __DATA__
   www.drane.fresel.co.uk
   www.drane2.ws.uk
   www.drane3.Intern.com
[download]

result:

www.drane.fresel.co.uk:         TLD is 'co.uk'
www.drane2.ws.uk:               TLD is 'ws.uk'
www.drane3.Intern.com:          TLD is 'com'
[download]

I use this in a Spam detection program. It gets allot more complicated than this!

Good Luck.

Your approach seems to fail for .de in one case and .name, .mobi, .museum in the other case. The only approach is to use a list of known TLDs.

I wasn't trying to be exhaustive. I was showing an approach for what he needed.

In the context of spam checking, it is the 3 and 5 letter TLDs that are the greatest problems.

But you are correct!

"Well done is better than well said." - Benjamin Franklin

I'm no Perl monk, and I'm sure there may well be better ways of doing it, but the code below might help. I expect there is some module out there with valid TLDs, but, regardless, if you happen to know each of the TLDs you'll be dealing with then you could do something like the code below maybe:

push (my @domains,'www.drane.fresel.co.uk','www.drane2.ws.ru','www.dra
+ne3.Intern.com');

for (@domains)
{
my $name=''; my $tld='';

    if ($_=~/\.co\.uk$/)
    {
    $name=substr($_,0,rindex($_,'co.uk')-1);
    $tld='co.uk';
    }
    elsif ($_=~/\.ws\.ru$/)
    {
    $name=substr($_,0,rindex($_,'ws.ru')-1);
    $tld='ws.ru';
    }
    elsif ($_=~/\.com$/)
    {
    $name=substr($_,0,rindex($_,'com')-1);
    $tld='com';
    }

print "\$name:\t$name\n\$tld:\t$tld\n\n";
}
[download]

... where you just read all your domain names into a list array, and then simply process the list.

Also be mindful of the (very large...) set of routines in CPAN under the category Regexp::Common.

In general, “if you are looking for a regular expression that you suspect probably has been written before, it probably has.”   And if you are looking for something that might need more than just a regular expression, i.e. programmed logic of some kind ... once again, CPAN probably already has it.   Therefore, get into this habit (and I sorely wish I could take my own advice):   look before you code.