[oak perl] Regular Expressions

[George Woolley]

Belden,
Thanks for getting things started!
And thanks also for including code as suggested!
And I see Tony's practice #1 embodied in your code.  :) :) :)

But I don't see any test cases as encouraged by practice #2.  :(
IMO, this would be very important 
if this were more than exercise.
It would also help you to clarify what you meant by word
in this context.

George

On Wednesday 10 March 2004 5:10 pm, Belden Lyman wrote:
> On Wed, 2004-03-10 at 12:55, Tony Stubblebine wrote:
> > Thanks George.
> >
> > I'm curious to see what sort of regular expressions people are writing,
> > good and bad. And I'd love to start a discussion on regex style or
> > technique.
>
> I wanted to find all 2 letter words in /usr/dict/words, so cut over
> to Perl after finding myself a few pipes deep:
>
>     $ grep '^..$' /usr/dict/words | grep -v '[A-Z][A-Z]' | grep -i
> '[aeiouy]'
>
> So long as I was doing this in Perl, I decided to make the program find
> all N-length words, with N defaulting to 2.
>
> If this looks like an exercise for someone learning (?=) and (?!),
> there's a reason for that ;)
>
>     #!/usr/bin/perl -s
>
>     use strict;
>     use warnings;
>
>     our $length;
>     $length = 2 unless $length;
>
>     @ARGV = '/usr/dict/words';
>
>     print grep {
>                 m/
>                  (?=^[A-Za-z]{$length}$)  # entry must be $length letters
> long (?!^[A-Z]+$)             # ignore all-caps words
>                  (?i-:                    # this next part is case
> insensitive: (?:                    #    we must have either [aeiouy].     
>       #      a vowel, then any letter
>
>                      |                    #      or
>
>                      .[aeiouy]            #      any letter, then a vowel
>                    )
>                  )
>                 /xo
>                }
>                (<>);
>
>     __END__
>
> Belden
>
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