Re: regular expressions

[toolic]

Your grep filters out entire lines. Do you have multiple words on each line? If so, all you need is one word on a line to have 4 consecutive consonants to get a match.

Another way, using a negated character class:

use warnings;
use strict;
use Data::Dumper;

my @words;
while (<DATA>) {
    chomp;
    push @words, grep { /[^aeiouy]{4}/i } split;
}

print Dumper(\@words);

__DATA__
abc def ghi AAAAAA
jlkm
opqr jhggjyg
123 annn jkjkkj bcdefgh

Prints:

$VAR1 = [
          'jlkm',
          'jhggjyg',
          'jkjkkj'
        ];

[Laurent_R]

I do not think that a negated character class is a good idea for looking for groups of consonants, because, for example, it will pick groups of digits, as shown below under the Perl debugger:

  DB<1> $_ ="123 annn jkjkkj bcdefgh 2015 ";

  DB<2> push @words, grep { /[^aeiouy]{4}/i } split;

  DB<3> x \@words;
0  ARRAY(0x600500b18)
   0  'jkjkkj'
   1  2015
  DB<4>

[AnomalousMonk]

I agree that doubly-negated character classes can be very tricky, but with care, they can be managed to good effect.

I think of it this way: Start with  [^\W] which is the same as  [\w] (or just \w). As you point out, this includes digits and _ (underscore) as well as alphas. "Subtract", as it were, the digits with  [^\W\d] and underscore with  [^\W\d_] and you're left with all alpha characters. Then subtract your chosen vowels  [^\W\d_aeiouyAEIUOY] and you're done!

c:\@Work\Perl\monks>perl -wMstrict -le
"my $s = '123 annn xyzzy wwwewww xxx9xxx vvv_vvv eieio p pp ppp 2015 v
+wxz vwxzpdq';
 ;;
 my $consonant = qr{ [^\W\d_aeiouyAEIUOY] }xms;
 ;;
 printf qq{'$_' } for $s =~ m{ $consonant{4,} }xmsg;
"
'vwxz' 'vwxzpdq'

All this is easier to manage, IMHO, with POSIX character classes or Unicode properties (if you're brave enough to venture out onto the thin, slippery ice of Unicode); both the following definitions work the same in the code above:
    my $consonant = qr{ [^[:^alpha:]aeiouyAEIUOY] }xms;
    my $consonant = qr{ [^\P{PosixAlpha}aeiouyAEIUOY] }xms;
YMMV. See perlrecharclass, perluniprops.

(See also the experimental Extended Bracketed Character Classes of version 5.18+; I can't give any examples using these ATM.)

[Laurent_R]

I agree with you, doubly-negated character classes can be tricky but can also be very useful. I was really reacting to the patterns proposed by Anonymous Monk and by toolic which were just not quite right.