Help with form validation regex

perlnewb123 has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Help with form validation regex by moritz (Cardinal) on May 11, 2009 at 17:18 UTC
`my $regex = qr{ \A # start of string .{3} # any 3 characters _ # underscore .*_ear # anything ending in _ear \z # end of string }xs;` [download] (Update: fixed ending of string)	[reply] [d/l]
Re: Help with form validation regex by mikeraz (Friar) on May 11, 2009 at 17:23 UTC
How about: `#!/usr/bin/perl while(<DATA>) { chomp; if( /\A[\w]{3}_\w+_ear\Z/ ) { print "$_ matches \n"; } else { print "no joy for $_ \n"; } } __DATA__ ab_wehave_noear abc_test_ear abc_test_two_ear abcc_test_ear` [download] which prints: `no joy for ab_wehave_noear abc_test_ear matches abc_test_two_ear matches no joy for abcc_test_ear` [download] I realize your problem definition said "characters" not "word thingies". I'm confident you can munge it to match your expected input range. Be Appropriate && Follow Your Curiosity	[reply] [d/l] [select]
Re^2: Help with form validation regex by JavaFan (Canon) on May 11, 2009 at 19:11 UTC
I wonder why you write: `[\w]{3}` instead of `\w{3}`.	[reply] [d/l] [select]
Re^3: Help with form validation regex by mikeraz (Friar) on May 11, 2009 at 21:51 UTC
So do I. The probable thought stream was an intent to specify more than \w and then discarding the idea without discarding the []. Bad Michael, no XP today. Be Appropriate && Follow Your Curiosity	[reply]
Re: Help with form validation regex by JavaFan (Canon) on May 11, 2009 at 18:03 UTC
`/^..._._ear$/s` [download] Or if the fourth character (`_`) may also be the fourth character from the end: `/^..._(?:._)?ear$/s` [download] Or even: `"_" eq substr($_, 3, 1) and "_ear" eq substr $_, -3;` [download]	[reply] [d/l] [select]
Re^2: Help with form validation regex by John M. Dlugosz (Monsignor) on May 11, 2009 at 18:20 UTC
Yes, he may have been a bit loose on what he meant by "any char". Maybe he meant word chars, or maybe he meant "any char except an underscore". But, you do show that the simplest answer isn't necessary a regex!	[reply]
Re^3: Help with form validation regex by perlnewb123 (Sexton) on May 11, 2009 at 18:57 UTC
Thanks everyone!	[reply]
Re^2: Help with form validation regex by johngg (Canon) on May 12, 2009 at 13:56 UTC
In your last code snippet I think the `... "_ear" eq substr $_, -3;` is only going to look at the last three characters so the condition will never be true. `$ perl -le ' $str = q{bit_of_a_pigs_ear}; print q{_ear} eq substr( $str, -3 ) ? q{Match found} : q{No match}; print q{_ear} eq substr( $str, -4 ) ? q{Match found} : q{No match};' No match Match found` [download] I hope this is of interest. Cheers, JohnGG	[reply] [d/l] [select]
Re: Help with form validation regex by dsheroh (Monsignor) on May 11, 2009 at 18:53 UTC
In what way is it "not really what [you] want"? Can you provide examples of cases in which your solution provides incorrect results (and what the correct results should be)?	[reply]