> Mushing this into a single regular expression is possible, by using [^sh] instead of dot

Do you mean   /s[^sh]*h/i ?

I doubt this, you would also need to check all characters before and after the match

  /^ [^sh]* s [^sh]* h [^sh]* $/xi *

Otherwise something like "h--<s--h>--s" should match in the middle. (Untested)

I think this demonstrates well why stuffing all logic into one regex is not always a good idea, particularly inversion isn't trivial.

footnotes

*) I just saw that tybalt89++ already posted this regex in this thread.

Yes - my post would have been much clearer had I also included the anchors and the (then explicit) .* before and after the matches.

Thank you for pointing this out and making it explicit!

Thanks to all that replied - Corion, great answer ~ I guess I am tired after a long week at work

#!/usr/bin/perl -w

my @words;
my $line;

open (DICT, "< final.txt");
@words= <DICT>;
close (DICT);

foreach $line(@words) {

  if ($line =~ /s.*h/i) {
        if ( ($line =~ /s.*s/i) || ($line =~ /h.*h/i) ) {
        next;
        }
  print $line;
  }
}

exit;
[download]

Produces some great words ha ha!

asthmatic
asthmatical
asthmatically
asthmatoid
asthmogenic
asthore
asthorin
astrachan
astrakhan
astraphobia
astraphobic
astrapophobia
astrochronological
...
crystallographically
crystallography
crystallophyllian
crystograph
ctesiphon
cubbish
cubbishly
cuemanship
cuish
cultish
cultishly
culture shock
cumshaw
cunctatorship
cuneoscaphoid
cuproscheelite
curateship
curatorship
curiosity killed the cat
[download]

Thanks! Nick

Hi Linicks,

a couple of a comments to improve your code.

open (DICT, "< final.txt");
[download]

Good practices nowadays recommend to use lexical file handles and the three-argument syntax for the open built-in function (and also to check that open succeeded):

open my $DICT, "<", "final.txt" or die "cannot open final.txt$!";
[download]

Second, if your file is large, it is a waste of resources (memory, CPU cycles and time) to store its contents into an array and then process the array, whereas you could just process directly the lines obtained from the file (unless you want to make several other searches on the same data):

open my $DICT, "<", "final.txt" or die "cannot open final.txt$!";
while (my $word = <$DICT>) {
    next unless $word =~ /s.*h/i;
    next if $word =~ /s.*s/i or $word =~ /h.*h/i;
    print $word;
}
[download]

You could also use a series of greps to filter your data:

open my $DICT, "<", "final.txt" or die "cannot open final.txt$!";
print for grep { not /h.*h/i } grep { not /s.*s/i }  grep /s.*h/i, <$D
+ICT>;
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or possibly only one grep with a composite condition.

Update: fixed the typo mentioned by Linicks: s/~=/=~/;.

Thanks, interesting. I see you also have the issue I have - _differnet_ typos ~

next if $word ~=

Heh.

My original code produces:

time perl sh.pl > sh.txt

real    0m3.770s
user    0m3.692s
sys    0m0.074s
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...and using the great sort of 4 liner while loop:

time perl sh.pl > sh.txt

real    0m4.192s
user    0m4.170s
sys    0m0.015s
[download]

seems slower.

Also, as to the error on open a file, I never bother when doing it in a terminal on a local machine as I know the file exists - in other circumstances I would, of course.

Thanks for your input!

Nick

P.S. The first word my dictionary file pulls up is abandon ship