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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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