UNIX for Dummies Questions & Answers

20110227
           20120528
           20141142
            20110230

use strict;
use warnings;
use Time::Local;

sub ckdate {
   my ($year, $mon, $mday) = @_;
   return join '', @_ if defined eval { timegm(0, 0, 0, $mday, $mon-1, $year); };
   return join '', '<span class="highlight">', @_, '</span>';
}

while (<>) {
   s{(\d{4})(\d\d)(\d\d)}{ckdate($1, $2, $3)}e;
   print;
}

20110227
           20120528
           <span class="highlight">20141142</span>
            <span class="highlight">20110230</span>

col1, col2,col3,date
1,2,3,20110825
2,3,4,20110229
6,8,9,20141142

use strict;
use warnings;
use Time::Local;

sub ckdate {
   my $date = shift @_;
   my ($year, $mon, $mday) = $date =~ m{^(\d\d\d\d)(\d\d)(\d\d)$};
   return unless defined $mday;
   return defined eval { timegm(0, 0, 0, $mday, $mon-1, $year); };
}

$, = ' ';
$\ = "\n";

while (<>) {
   chomp;
   my @F = split ',';
   next if ckdate pop @F;
   print '?', $_;
}

sub ckdate {

   my $date = shift @_;
   my ($year, $mon, $mday) = $date =~ m{^(\d\d\d\d)(\d\d)(\d\d)$};

   return unless defined $mday;

   return defined eval { timegm(0, 0, 0, $mday, $mon-1, $year); };

   my @F = split ',';

   next if ckdate pop @F;

    print '?', $_;

col1, col2,col3,date
1,2,3,20110825
2,3,4,20110229
6,8,9,20141142