Hi Stevieb,

I wasn't considering performance but rather the ease of maintenance of a list of items. The OP has $targets (plural) as the name of his string, so I assumed that at some point he had a list, and then put it into a string.

I agree that if he originally had a string like that (e.g. from a log file) then a regexp would be the way to find a substring of it.

But if he has a list then putting it into a string and looking for a match is headed in the wrong direction, IMO.

Update: I wanted to know, so now I do. In this case join()ing the list into a string and then using a regexp is still much faster than populating a hash:

use Benchmark qw(:all);

cmpthese ( 5000000, {
  'string' => 'string()',
  'hash' => 'hash()',
  'list2string' => 'list2string()',
});

# other subs as before

sub list2string {
  my $str = join( ' ', qw/1689 9679 2792 2514 5472 1520 9342 5544 1268
+ 0165 1979 7314 2101 7221 9539 3882 1812/ );
  my $test = 2101;
  if ($str =~ $test){
    # do stuff
  }
}

__END__

                 Rate                         hash list2string      st
+ring
                 hash          62406/s          --        -88%        
+-95%
                 list2string  530223/s        750%          --        
+-61%
                 string      1355014/s       2071%        156%        
+  --
[download]

But I still wouldn't do it myself as combining discrete values into a string just feels wrong.