in reply to Creating a regex to match part of a URL's domain name (was: pattern matching)

Well, putting aside your desire to match the "important" part of a domain name, you probably want to use a regex that says "match and save a set of non-. characters that are followed by a ., then non-. and non-/ characters, and then either a / or the end of the string".

Basically, you want to ensure you're a) only looking at the domain name, and b) getting the penultimate .-separated sequence.

It would probably be more intuitive to use two split()s: 
($domain) = split '/', $string;
$wanted = (split /\./, $domain)[-2];

# or

$wanted = (split /\./, (split '/', $string)[0])[-2];

[download]
Here's the regex approach: 
($wanted) = $string =~ m{
  ( [^.]+ )   # save the non-. sequence to $1
  \.          # .
  [^./]+      # the final non-. non-/ sequence
  (?: / | $)  # / or the end of the string
}x;

[download]


japhy -- Perl and Regex Hacker

Replies are listed 'Best First'.
Re: Re: pattern matching
by strfry() (Monk) on Jun 06, 2001 at 19:50 UTC
    hmm i used part of your code in a subroutine, and it's giving me the error "Use of uninitialized value at ./index.cgi line 29."
    here's the function:
    sub getd {

my $string = @_;
my $wanted;
my $domain;

($domain) = split '/', $string;
$wanted = (split /\./, $domain)[-2];

return $wanted;
}

my $variable = "www.google.com";
print &getd($variable);   # this is line 29.

    [download]

    any ideas?

    strfry()
[reply]
[d/l]
      You're not doing any rudimentary data-checking, or you'd see that my $string = @_ was assigning a number to your variable. 
      # try one of these:

my ($string) = @_;
my $string = shift;
my $string = $_[0];

      [download]


      japhy -- Perl and Regex Hacker
[reply]
[d/l]
        aha! but what if i want to use
        my $variable = "http://www.google.com"; ? does this subroutine not handle "/"'s?
[reply]
[d/l]
Re: Re: pattern matching
by strfry() (Monk) on Jun 06, 2001 at 18:48 UTC
    yes yes yes yes! that's it! thank you! (:
    now all i have to do is fiddle with it until i understand exactly what's taking place hehe
    gracias

    strfry()
[reply]

In Section Seekers of Perl Wisdom