use Date::Calc qw/Delta_Days/;
use strict;

my @date1 = (2007, 12, 24); # or split '-', '2006-12-24';
my @date2 = (2009, 4, 16);  # or split '-', '2009-4-16';
my $days  = Delta_Days(@date1, @date2);

print "There are $days days between ".
  sprintf('%04d-%02d-%02d',@date1)." and ".
  sprintf('%04d-%02d-%02d',@date1).".\n";