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Re: RegEx for users who dont know RegEx

by The Mad Hatter (Priest)
on Dec 23, 2004 at 17:18 UTC ( [id://417158]=note: print w/replies, xml ) Need Help??

in reply to RegEx for users who dont know RegEx

One solution is to strip out all characters in the user-supplied data that aren't explicitly allowed and then generate your regex based off of that.

Update -- Try this sample code:

#!/usr/bin/perl use warnings; use strict; my $query = shift; die "usage: $0 query-string\n" if not $query; print "Original query: '$query'\n"; $query =~ s/[^\w\*]//g; print "Safe query: '$query'\n"; $query =~ s/\*/\\w\*/g; print "Parsed query: '$query'\n"; while (<DATA>) { print "match: $_" if /$query/i; } __DATA__ invitation information Isolation InFlaTiOn IATION In our nation it requires concentration at ionizing radiation
Note that "at ionizing radiation" matches because the iation in radiation matches. Did you just miss that, or should it not match?

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Re^2: RegEx for users who dont know RegEx
by ikegami (Patriarch) on Dec 23, 2004 at 17:30 UTC
    Why strip out the unsafe characters instead of escaping them, as I did below? Using your approach to search for "can't" will fail, for example.
      *shrugs* Stripping out unsafe characters just seems like a better idea; you know exactly what you're left with. If you want to allow single ticks or other characters, modifying the regex of allowed chars is easy. The code above is just an example, not a final product.

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