use warnings;
use strict;

# test routine
for my $y (2001..2002){
  for my $m (1,6,12){
   for my $d (1,15,16,31){
     print "$d\t$m\t$y = ".newrelease($d,$m-1,$y-1900)."\n";
   }
  }
  print "\n";
}

sub newrelease {
  #my ($day,$month,$year) = (localtime)[3,4,5];
  my ($day,$month,$year) = @_; # testing
  # make normal
  $year+=1900;
  $month+=1;

  # return values
  my ($start_date,$end_date);

  # logic
  if ($day > 15){
    # easy one same month
    $month = sprintf "%02d",$month;
    $start_date = $year.$month."01";
    $end_date   = $year.$month."15";
  } else {
    # day is 15 or less use previous month
    # if now jan then prev month is dec last year
    if ($month == 1){
      --$year;
      $month=12;
    } else {
      $month = sprintf "%02d",$month-1;
    }
    $start_date = $year.$month."16";
    $end_date   = $year.$month."31";
  }
  return "$start_date to $end_date";
}