Well, I hate to be the bad guy, but I think a comment is needed here. There are several problems with the above code:

  1. It doesn't work, even as designed (it's only getting the first line from the file, because <DOC> is in scalar context)
  2. It's bad style
    • Aside from the error in reading the file, the binmode is dubious
    • Assuming the intent is really to slurp the entire file, that's generally not a good thing to do -- and that's not a good idiom to use to do it
    • Use of .*? in a REx is almost always a bad choice -- here it should be [^>]*
  3. It's shockingly inefficient -- if you're up for some fun, run it through re 'debug' some time
  4. Finally, and most importantly, it's wrong. I added a print statement and closed the while (and fixed the slurping error) and ran the following perfectly valid HTML through it: 
    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<HEAD><TITLE>Test</TITLE></HEAD>
<BODY>
<a href  ="foobaz"></a>
<a name="href=foo"></a>
<a name="foo>bar" href="foobar"></a>
</BODY>
</HTML>

    [download]
    And it missed the two valid href links (the first and the last) and wrongly flagged the second one as an href link.

I think it's very important to realize that while doing this sort of thing seems easy, it isn't. There are a lot of cases that you will miss if you try. Use LinkExtor. Use HTML::Parser. Use HTML::TokeParser. Heck, use URI::Find. Just don't "do it yourself" unless you're prepared to devote quite a bit of time developing, honing, and fixing your solution.

I think that Dermot knows all of this, judging from his comment that using the CPAN is probably the best way to go, but I wanted to make sure no one decided to use this instead because it was "easier". Do not.

I leave you with something I posted to Usenet not too long ago -- a script that correctly finds all anchor links in a document -- in 4 lines of Perl. It's that easy to do with HTML::Parser or one of the other tools made for such things.

-dlc 

#!/usr/bin/perl -wl
use strict;use HTML::Parser;my $p=HTML::Parser->new(api_version
=>3);$p->handler(start=>sub{print shift->{href}if shift eq 'a'},
'tagname,attr');local $/;$p->parse(<>);#Just another URI finder

[download]

In reply to Re: Re: How can I find the links in HTML tags? by dchetlin
in thread How can I find the links in HTML tags? by Anonymous Monk

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