#!/usr/bin/perl
use strict;
use warnings;

my $lies    = "C:\\Batch\\Perl\\Werte.txt";
my $schreib = "C:\\Batch\\Perl\\neu.txt";

open my $DATEI, "<", $lies     or die "$lies: $!";
open my $REIN,  ">", $schreib  or die "$schreib: $!";

while (my $string = <$DATEI>) {

   my ($D,$M,$Y)= $string =~ /^(\d\d?)\.(\d\d?)\.(\d{2,4})/;

   if (not defined $Y) {
         ($Y,$M,$D)= $string =~ /^(\d{4})(\d{2})(\d{2})/;
      }
   $anordnen = sprintf "%d.%d.%d", $D, $M, $Y;
   print "$anordnen\n";
   push @array, $anordnen;
}

print $REIN @array or die "print failed: $!";

close $DATEI;
close $REIN or die "$schreib: $!";