$flds[16] = undef;
$flds[8] = 0;

##</code><code>##

$flds[8] = 0;
$flds[16] = undef;

##</code><code>##

use warnings;
use strict;

use Data::Dumper;

my $value = "A\tB\tC\tD\tE\tF\t\t\t\t";
my @flds = split(/\t/,$value);

for (0..16){
    $flds[$_] = undef if ! defined $flds[$_];
}

$flds[8] = 0;

print Dumper \@flds;

##</code><code>##

$VAR1 = [
          'A',
          'B',
          'C',
          'D',
          'E',
          'F',
          undef,
          undef,
          0,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef,
          undef
        ];