sub DateNext {
  my ($y, $m, $d) = unpack('a4a2a2', $_[0]);
  my @daysinmonth = ("31","28","31","30","31","30","31","31","30","31","30","31");
  my @daysinmonthly = ("31","29","31","30","31","30","31","31","30","31","30","31");
  $d++;
  if (($y % 4) == 0) {
    if ($d > @daysinmonthly[$m - 1]) {
      $m++;
      if ($m > 12) {
        $m = 1;
        $y++;
      } ## End if
      $d = 1;
    } ## End if
  } ## End if
  else {
    if ($d > @daysinmonth[$m - 1]) {
      $m++;
      if ($m > 12) {
        $m = 1;
        $y++;
      } ## End if
      $d = 1;
    } ## End if
  } ## End else
  my $returndate = sprintf("%04d%02d%02d",$y,$m,$d);
  return $returndate;
} ## End sub

### Brings date to the previous day
sub DatePrevious {
  my ($y, $m, $d) = unpack('a4a2a2', $_[0]);
  my @daysinmonth = ("31","28","31","30","31","30","31","31","30","31","30","31");
  my @daysinmonthly = ("31","29","31","30","31","30","31","31","30","31","30","31");
  $d--;
  if (($y % 4) == 0) {
    if ($d < 1) {
      $m--;
      if ($m < 1) {
        $m = 12;
        $y--;
      } ## End if
      $d = @daysinmonthly[$m - 1];
    } ## End if
  } ## End if
  else {
    if ($d < 1) {
      $m--;
      if ($m < 1) {
        $m = 12;
        $y--;
      } ## End if
      $d = @daysinmonth[$m - 1];
    } ## End if
  } ## End else
  my $returndate = sprintf("%04d%02d%02d",$y,$m,$d);
  return $returndate;
} ## End sub