how to use regular expressions read some string from a htm file

weihe has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: how to use regular expressions read some string from a htm file by GrandFather (Saint) on Aug 02, 2006 at 05:13 UTC
You don't. You use HTML::TreeBuilder or some such similar module. Life is too short to bother reinventing that particular wheel. Markup is hard to write regexen to parse because there are many special cases for handling things like white space. Try something like: use strict; use warnings; use HTML::TreeBuilder; my $str = <<'STR'; <html><head><title>my page></title></head> <body> <table><tr><td> <a href="http://mysite/bbsui.jsp?id=dxpwd">dxpwd</a> </td><td> <a href="http://mysite/bbsui.jsp?id=jimeth">jimeth</a> </td><td> <a href="http://mysite/bbsui.jsp?id=jone28">jone28</a> </td><td> <a href="http://mysite/bbsui.jsp?id=25528">25528</a> </td></tr> </body></html> STR my $tree = HTML::TreeBuilder->new; $tree->parse ($str); print $_->attr ('href') . "\n" for $tree->find ('a'); [download] Prints: `http://mysite/bbsui.jsp?id=dxpwd http://mysite/bbsui.jsp?id=jimeth http://mysite/bbsui.jsp?id=jone28 http://mysite/bbsui.jsp?id=25528` [download] DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
A reply falls below the community's threshold of quality. You may see it by logging in.
Re: how to use regular expressions read some string from a htm file by Zaxo (Archbishop) on Aug 02, 2006 at 05:10 UTC
Don't use a regular expression, `use HTML::LinkExtor;` It will drive you mad to try this with regexen. After Compline, Zaxo	[reply]
Re: how to use regular expressions read some string from a htm file by reneeb (Chaplain) on Aug 02, 2006 at 05:48 UTC
You can use HTML::Parser: #! /usr/bin/perl use strict; use warnings; use HTML::Parser; my @links; my $string = qq~<a href="url1">linktext1</a> Ein anderer Text <a href="url2">linktext2</a> text~; my $p = HTML::Parser->new(); $p->handler(start => \&start_handler,"tagname,attr,self"); $p->parse($string); foreach my $link(@links){ print "Linktext: ",$link->[1],"\tURL: ",$link->[0],"\n"; } sub start_handler{ return if(shift ne 'a'); my ($class) = shift->{href}; my $self = shift; my $text; $self->handler(text => sub{$text = shift;},"dtext"); $self->handler(end => sub{push(@links,[$class,$text]) if(shift eq 'a +')},"tagname"); } [download]	[reply] [d/l]
Re: how to use regular expressions read some string from a htm file by rsriram (Hermit) on Aug 02, 2006 at 05:34 UTC
Hi, It is a smarter way to use modules instead of regular expressions when working with HTML files. But, if you are so particular in using regex, try this. `open (F1, "<$ARGV[0]") \|\| die ("Can't open the file $ARGV[0]. $!\n");` `while(<F1>)` `{` `print "$1\n" if ($_ =~ /<a href="([^"]+)">/)` `}` `close F1;` In the above script, I have the HTML file stored in the variable `F1`.	[reply] [d/l] [select]
Re: how do i get special string from source of text file by gellyfish (Monsignor) on Aug 02, 2006 at 08:09 UTC
I'd suggest using HTML::LinkExtor to extract the URLs from the `<a />` elements and then throwing away the ones you don't want afterwards, however as you don't say how to distinguish between the ones you do want and the ones you don't I'm not going to guess and give you an example. /J\	[reply] [d/l]
Re: how to use regular expressions read some string from a htm file by planetscape (Chancellor) on Aug 02, 2006 at 17:45 UTC
As many others have pointed out, you don't. In addition to the other excellent examples above, you could also use mech-dump, which comes with WWW::Mechanize, e.g.: `mech-dump --links http://www.perlmonks.org` You would still, of course, need to do some post-processing to get just the links you want, but so far you have posted no criteria to determine which of those that is. HTH, planetscape	[reply] [d/l]