[regex-coach] alternations working differently in Regex Coach versus perl program.

[Edi Weitz]

Sorry for the delay.  I was on vacation and/or out of town most of the time.

Your regex is wrong.  The hyphen is part of one of the alternatives
(e.g. it's "10" OR "12-[012]..." and so on) which I think is not what
you want.

The Perl program behaves like the Regex Coach, but you don't see it.
Try replacing the line 'print "okay\n"' with 'print "okay[$']\n"'
(note the apostrophe there).

HTH,
Edi.



On Sun, Aug 2, 2009 at 8:35 PM, Troy Peterson
<troypennpeterson at gmail.com> wrote:
> I am writing a regex to test for valid dates in YYYY-MM-DD format.
> Using this regex in a perl test program I get positive results for all dates
> for the next 365 days.
> Regex Coach however failes to match some such as '2010-06-30'.  I assume
> this is because of the  order of the alternations and the regex wanting to
> match a sub-pattern as quickly as possible.  I can resolve the issue in The
> Regex Coach by adding () around the month and year patterns.
> I would like to know why there is a difference between my Perl program and
> Regex Coach.  Could this be implementation dependent.  Both my program and
> its output are below.
> I tend to think that The Regex Coach got this right.
> (?# regex in The Regex Coach)
>         [123456789]\d\d\d-                                           # year
>          (?:
>             (?:0[13578]|10|12 -  [012][123456789]|10|20|30|31)  |      #
> Months with 31 days
>             (?:0[469]|11      -  [012][123456789]|10|20|30   )  |      #
> Months with 30 days
>             (?:02             -  [012][12345678]||10|20|19   )         #
> Febuary
>          )
> ### perl Test program
> #!/iw-home/teamsite/iw-perl/bin/iwperl
> use strict;
> use warnings;
> use Carp;
> use Getopt::Long;
> use Pod::Usage;
> use Cwd;
> use Date::Calc qw(:all);
> my $dateregex = qr{
>         [123456789]\d\d\d-                                           # year
>          (?:
>             (?:0[13578]|10|12 -  [012][123456789]|10|20|30|31)  |      #
> Months with 31 days
>             (?:0[469]|11      -  [012][123456789]|10|20|30   )  |      #
> Months with 30 days
>             (?:02             -  [012][12345678]||10|20|19   )         #
> Febuary
>          )
> }smx;
> sub testdate {
>     my ($d) = (@_);
>     print "$d";
>     if ( $d =~ m{$dateregex}smx ) {
>         print "okay\n";
>     }
>     else {
>         print "\n";
>         croak "broken";
>     }
> }
> foreach my $d ( 1 .. 365 ) {
>     my ( $year, $month, $day, $hour, $min, $sec, $doy, $dow, $dst ) =
>       System_Clock();
>     ( $year, $month, $day, $hour, $min, $sec ) =
>       Add_Delta_DHMS( $year, $month, $day, '0', '0', '0', "$d", '0', '0',
> '0' );
>     my $td = sprintf( "%4d-%02d-%02d", $year, $month, $day );
>     testdate("$td");
> }
> exit;
>
> ##OUTPUT
> 2009-08-03okay
> 2009-08-04okay
> 2009-08-05okay
> 2009-08-06okay
> 2009-08-07okay
> 2009-08-08okay
> 2009-08-09okay
> 2009-08-10okay
> 2009-08-11okay
> 2009-08-12okay
> 2009-08-13okay
> 2009-08-14okay
> 2009-08-15okay
> 2009-08-16okay
> 2009-08-17okay
> 2009-08-18okay
> 2009-08-19okay
> 2009-08-20okay
> 2009-08-21okay
> 2009-08-22okay
> 2009-08-23okay
> 2009-08-24okay
> 2009-08-25okay
> 2009-08-26okay
> 2009-08-27okay
> 2009-08-28okay
> 2009-08-29okay
> 2009-08-30okay
> 2009-08-31okay
> 2009-09-01okay
> 2009-09-02okay
> 2009-09-03okay
> 2009-09-04okay
> 2009-09-05okay
> 2009-09-06okay
> 2009-09-07okay
> 2009-09-08okay
> 2009-09-09okay
> 2009-09-10okay
> 2009-09-11okay
> 2009-09-12okay
> 2009-09-13okay
> 2009-09-14okay
> 2009-09-15okay
> 2009-09-16okay
> 2009-09-17okay
> 2009-09-18okay
> 2009-09-19okay
> 2009-09-20okay
> 2009-09-21okay
> 2009-09-22okay
> 2009-09-23okay
> 2009-09-24okay
> 2009-09-25okay
> 2009-09-26okay
> 2009-09-27okay
> 2009-09-28okay
> 2009-09-29okay
> 2009-09-30okay
> 2009-10-01okay
> 2009-10-02okay
> 2009-10-03okay
> 2009-10-04okay
> 2009-10-05okay
> 2009-10-06okay
> 2009-10-07okay
> 2009-10-08okay
> 2009-10-09okay
> 2009-10-10okay
> 2009-10-11okay
> 2009-10-12okay
> 2009-10-13okay
> 2009-10-14okay
> 2009-10-15okay
> 2009-10-16okay
> 2009-10-17okay
> 2009-10-18okay
> 2009-10-19okay
> 2009-10-20okay
> 2009-10-21okay
> 2009-10-22okay
> 2009-10-23okay
> 2009-10-24okay
> 2009-10-25okay
> 2009-10-26okay
> 2009-10-27okay
> 2009-10-28okay
> 2009-10-29okay
> 2009-10-30okay
> 2009-10-31okay
> 2009-11-01okay
> 2009-11-02okay
> 2009-11-03okay
> 2009-11-04okay
> 2009-11-05okay
> 2009-11-06okay
> 2009-11-07okay
> 2009-11-08okay
> 2009-11-09okay
> 2009-11-10okay
> 2009-11-11okay
> 2009-11-12okay
> 2009-11-13okay
> 2009-11-14okay
> 2009-11-15okay
> 2009-11-16okay
> 2009-11-17okay
> 2009-11-18okay
> 2009-11-19okay
> 2009-11-20okay
> 2009-11-21okay
> 2009-11-22okay
> 2009-11-23okay
> 2009-11-24okay
> 2009-11-25okay
> 2009-11-26okay
> 2009-11-27okay
> 2009-11-28okay
> 2009-11-29okay
> 2009-11-30okay
> 2009-12-01okay
> 2009-12-02okay
> 2009-12-03okay
> 2009-12-04okay
> 2009-12-05okay
> 2009-12-06okay
> 2009-12-07okay
> 2009-12-08okay
> 2009-12-09okay
> 2009-12-10okay
> 2009-12-11okay
> 2009-12-12okay
> 2009-12-13okay
> 2009-12-14okay
> 2009-12-15okay
> 2009-12-16okay
> 2009-12-17okay
> 2009-12-18okay
> 2009-12-19okay
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> 2009-12-27okay
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> 2010-01-01okay
> 2010-01-02okay
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> 2010-01-30okay
> 2010-01-31okay
> 2010-02-01okay
> 2010-02-02okay
> 2010-02-03okay
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> 2010-03-01okay
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