my @tests = qw/ p up hip hop hoop heap help hops /; 

for ( @tests ) {
  say if reverse =~ /^p([aeiou])(?!\1)/;
}
[download]

Gooooood thinking, Not_a_Number!!!!

I like this one ... reversing the string before matching it ... how neat is that? Excellent! Goooood on ya! And thanks for the idea. This is coooooool stuff!

And who ever said 'regex golfing was a waste of time'? Far from it ... it's like Perl philosophy ... pure aesthetics ... sheer bliss. Thanks agani for this near little twist!

use warnings;
use strict;

while (<DATA>) {
    chomp;
    if (/[^aeiou][aeiou]p$/i) {
        print "$_ match\n";
    }
    else {
        print "$_ no match\n";
    }
}

__DATA__
carp
step
tip
stoop
steep
asp
food
mop
up
[download]

carp no match
step match
tip match
stoop no match
steep no match
asp no match
food no match
mop match
up no match
[download]

Yeah, sorry ... same thing: by 'double vowel' I meant the same vowel occurring twice ...

If you define vowel as one of 'a', 'e', 'i', 'o' and 'u' (because I know some other monks will point out that I'm being anglocentric :)), a regex that fits your criteria is:

Please adjust for case sensitivity as necessary.

Edit: Did you mean two vowels in a row or the same vowel twice before the 'p'? The regex above solves the former, but not the latter.

Hi, AR -

Thanks for your proposal ... but that's not precisely what I wanted ... I do want words like 'feap' to pass ... only words in which the same vowel is duplicated before the 'p' should be filtered out. Sorry for not making this perfectly clear right from the start.

Any alternative suggestions from your side then?

Cheers -

Pat

/((\b|[^aeiou])[aeiou]|[eiou]a|[aiou]e|[aeou]i|[aeiu]o|[aeio]u)p\b/

but it's not even remotely elegant. I'll keep working on it.

local $_= "Stop tip stoop put up, tops steep 'creap' sleep soap!";
my @words;
push @words, $1
#   while  /(\b\w*(?!(.)\2)\w[aeiou]p\b)/g;
    while  /(\b(?:\w*(?!(.)\2)\w)?[aeiou]p\b)/g;
print "( @words )\n";
__END__
( Stop tip up creap soap )
[download]

Update: Changed . to \w so would not match, for example, "no-op" (if you want '-' allowed in words, then replace \w with, for example, [-\w] both places). Then: added (?:...)? to match two-letter words (since my original attempt that handled two-letter words fails because (?<!\2) is not smart enough to realize the fixed length of \2).

Here are some other ways to do it, including one that doesn't work and one that almost works...

local $_= "Up stop 'Oop' tip stoop put\nup, tops steep 'creap' sleep s
+oap!";
my @words;
push @words, $1
            # Misses "up" if first word in string:
#   while  /(\b\w*(?<=(.))(?!\2)[aeiou]p\b)/gi;
            # Would work if (?<=...|...) were smarter:
#   while  /(\b\w*(?<=^|(.)(?!\2))[aeiou]p\b)/gsi;
            # How to work around (?<=...|...) being dumb:
#   while  /(\b\w*(?:(?<=^)|(?<=(.)(?!\2)))[aeiou]p\b)/gsi;
            # (?<=^) can be shortened to just ^:
    while  /(\b\w*(?:^|(?<=(.)(?!\2)))[aeiou]p\b)/gsi;
            # Or just skip the complex check for 2-letter words:
#   while  /(\b(?:\w*(?<=(.))(?!\2))?[aeiou]p\b)/gsi;
print "( @words )\n";
__END__
( Up stop tip up creap soap )
[download]

- tye        

I've not done much testing but this seems to work by putting the capture in the look-behind.

knoppix@Microknoppix:~$ perl -E '
> for ( qw{ soap creep top groat loop } )
> {
>     say unless m{(?<=([aeiou]))\1p\z};
> }'
soap
top
groat
knoppix@Microknoppix:~$
[download]

I hope this is helpful.

    say unless m{(?<=([aeiou]))\1p\z};

That allows eg 'help' or slurp'.

Update: I've no idea why though, or why it also allows 'hops' and 'hoops'...

Update 2: Got it! It also of course allows 'rabbit', or any other string that doesn't end in 'p' preceded by whatever. It was the unless that momentarily confused me. :)

Yes, that was a pretty woeful attempt on my part. I must have been thinking about a sub-set of words all ending with 'p' rather than the general case :-(

Cheers,

JohnGG

Hi, johngg -

I like the approach of back-referencing the match from the look-behing ... the only issue I have with the code you propose is that it over-generates in the sense that it will also pass strings all other strings that do not match the regex like 'stp' ... and that, of course, it shouldn't since we only want words to pass that have a non-double vowels in front of the word-terminal 'p'.

Can you solve your problem, sufficiently well, using a combination of regexes and procedural code?   One regular expression could, for example, locate all source lines in the document which contain “a vowel that is not immediately followed by another vowel,” leading to an if-statement in which the matching lines are further examined by whatever means seem appropriate.

Sure, “regex golf” is instructive.   It can even be entertaining.   But it can also devolve into a waste of time...

The answer would be "Yes" on all accounts :-)