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Re: Regex help

by Anonymous Monk
on Oct 01, 2002 at 23:40 UTC ( #202151=note: print w/replies, xml ) Need Help??


in reply to Re: Re: Regex help
in thread Regex help

Nope. The parenthesis are optional, but can be VERY useful. For example, say you want to remove the <script> and </script>, but be able to give some sort of warning about the script tags. For example, you may filter out:
<script> malicious_code_to_do_something_nasty </script>
If you use your regex as <script>(.*?)</script>, it saves the smallest amount (the ?) of anything (the .*) into a variable. That variable name depends on how many sets of parenthesis you've used. If it's the first (and only) time you use them, it gets saved into $1. If the second time, $2, and so forth. You can use it for something like this:
$text = "my name is john q user\n"; $text =~ s/^my name is (.*?) .*$/$1/; # removes "my name is ", saves the next word, essentially, into $1, re +moves the rest print "hello, $text!\n"; # prints "hello, john!\n"
This is VERY useful in extracting information from strings.


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[Lady_Aleena]: Your Mother, that's the command line grep, not perl's grep.
[Your Mother]: …how on Earth could Perl’s grep recurse?
[Tanktalus]: perldigious: I'm not looking to get rich. I'm looking for interesting work, with good continuity of employment, and maintenance of our current lifestyle. (An improvement wouldn't be bad, either, but that's not a requirement ;) )
erix enjoys the confusion++
[Your Mother]: :P
[Tanktalus]: Without confusion, I'd be out of a job ;)
[Tanktalus]: Already. :D
[Lady_Aleena]: Your Mother, I wish it did have a way to put in a directory to search.
[Your Mother]: That’s silly. It’s a string op tool.
[Lady_Aleena]: So I guess I'll go argue with File::Find and grep.

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