Hi,

I am a newbie on perl and trying to understand regular expression usage, how it works and also trying to accomplish a task of converting an html page into an RSS feed. I came accross a script which does conversion for known sites and one could modify the script to add more sites. All one needs to do is add the details of formatting to capture.

A portion of the code written in the program is detailed below

Parameters Passed
$url = http://www.sfgate.com/examiner/bondage/
$html = Is the content of the URL specified

Can someone help me document each section of the following code. And If had to do something like this for the URL http://bsewebx.bseindia.com/qresann/announce.asp what would the code look like and what would be the changes.

sub do_bondagefiles {
  my ($url, $html) = @_;

  $_ = $html;

  1 while (s@<!--.*?-->@ @gsi);  # lose comments

  s/[\r\n]+/ /gs;

  s@^.*?(<A HREF=\"[^\"]*article\.cgi)\b@$1@is ||
    error ("unable to trim head in $url");
  s@<[^<>]*\bblacktri\.gif\b.*$@@is ||
    error ("unable to trim tail in $url");

  s@(<A\b[^<>]*\bHREF\b)@\n\001\001\001\n$1@gi;

  my @sec1 = split (/\n\001\001\001\n/s);
  my @sec2 = ();
  foreach (@sec1) {
    next if (m/^\s*$/s);

    s@^\s*<A\b[^<>]*?\bHREF=\"([^<>\"]+)\"[^<>]*>\s*(.*?)\s*</A>\s*@@i
+s ||
      error ("unparsable entry (url) in $url");
    my $eurl  = $1;
    my $title = $2;
    my $date  = '';
    my $body  = $_;

    $body =~ s@<[^<>]*>@@g;  # lose tags in body

    push @sec2, ($eurl, $date, $title, $body);
  }

  return @sec2;
}

[download]
Thanks for helping this newbie. Cheers.

In reply to Understanding Regular Expressions by Anonymous Monk

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