There is a difference, but it's not necessarily in what is getting matched, but rather, in how it's matching. Example: 

use strict;
use warnings;

my @strings = (
  "____\n",   "__ __\n",  "__X __\n",
  "__Z__\n",  "__\n__\n", "__^__\n",
  "_____\n",  "________\n",
); 


foreach my $string ( @strings ) {
  print "<<$string>>\n";
  if( $string =~ m/__(\S+?)__/ ) {
    print "\tNon-Greedy -- Match: (($1)).\n";
  }
  else {
    print "\tNon-Greedy -- No Match.\n";
  }
  if( $string =~ m/__(\S+)__/ ) {
    print "\tGreedy     -- Match: [[$1]].\n";
  }
  else {
    print "\tGreedy     -- No Match.\n";
  }
}

[download]

Most of that is going to be pretty boring, until you get to the last item in the list, where you'll get the following output:

<<________
>>
    Non-Greedy -- Match: ((_)).
    Greedy     -- Match: [[____]].

[download]

I have no idea whether non-greedy matching is going to have any practical effect in the type of strings you're matching with the regex though.


Dave

In reply to Re: Puzzled by regex by davido
in thread Puzzled by regex by syphilis

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