Newbie regex question

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

Greetings Monks,

I'm a Perl Novice, and I have a problem with a regex. I wanted my program to extract text from a file (which holds the content of a web page) and find a delimited string.

open(FILE1, "<raw.txt");
$text = <FILE2>;
if ($text =~ /birthdate(.*?)zodiac/i)
    {
     my $birthdate = $1;
     }
    open(FILE2, ">>births.txt");
    print FILE2 $birthdate;
[download]

What am I doing wrong? I know this is very basic, but I've been looking for an answer and reading about regexes, to no avail.

Cheerio, Marcin

Comment on Newbie regex question Download Code

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Re: Newbie regex question by Corion (Patriarch) on Jan 15, 2011 at 16:54 UTC
`use strict;` at the top of your program would catch your error and point out the location where you need to think about what you're doing. You'll need to declare `$birthdate` outside of your block, and not declare it twice, because the inner declaration shadows the outer declaration for its block.	[reply] [d/l] [select]
Re: Newbie regex question by toolic (Bishop) on Jan 15, 2011 at 16:57 UTC
use strict and warnings. This will show you that your `$birthdate` variable is out of scope Why do you think there is a problem with your regex? `use strict; use warnings; my $text = 'birthdate1234zodiac'; if ($text =~ /birthdate(.*?)zodiac/i) { my $birthdate = $1; print "$birthdate\n"; } __END__ prints: 1234` [download] If that's not the problem, then you should show us a small sample of your input file. You would also benefit from running your code through perltidy and perlcritic.	[reply] [d/l] [select]
Re^2: Newbie regex question by Anonymous Monk on Jan 15, 2011 at 17:05 UTC
Thank you, obviously the variable was out of scope. So much for not using strict and warnings. Cheers!	[reply]
Re: Newbie regex question by eff_i_g (Curate) on Jan 15, 2011 at 19:06 UTC
As a newbie you may also want to `use diagnostics;` in times like these. Also, as you get more entrenched (smitten?) with Perl, you'll want to scour CPAN's plethora of parsing modules rather than using quick-and-dirty regexes (although, they will always have their place).	[reply] [d/l]
Re: Newbie regex question by planetscape (Chancellor) on Jan 17, 2011 at 08:58 UTC
extract text from a file (which holds the content of a web page) You probably don't really want to parse HTML with regexes, at least as a matter of habit. Instead, use something suited to handling HTML, like HTML::TreeBuilder or HTML::TokeParser::Simple. Other good advice may be found by Super Searching for "don't parse HTML regex". HTH, planetscape	[reply]