use strict;
use warnings;
use Date::Calc qw( Date_to_Days );

my ($jahr1,$monat1,$tag1) = (2009,3,15);
my ($jahr2,$monat2,$tag2) = (2009,4,30);

my $lower = Date_to_Days($jahr1,$monat1,$tag1);
my $upper = Date_to_Days($jahr2,$monat2,$tag2);

my $date = Date_to_Days(2009,5,2);

if (($date >= $lower) && ($date <= $upper))
  { print "OK\n"; }
else
  { print "FAIL\n"; }