use Date::Parse;
use Date::Calc qw(Delta_Days);

use strict;

my $base = 'Jan 1, 1980';
my $start = 'Feb 1, 1981';
my $end = 'Feb 5, 1982';

print days_diff($start, $base) . "\n"; # 397
print days_diff($end, $base) . "\n"; # 766

sub days_diff {
	my $minuend = shift;
	my $subtrahend = shift;
	
	my (undef,undef,undef,$d2,$m2,$y2,undef) = strptime($minuend);
	my (undef,undef,undef,$d1,$m1,$y1,undef) = strptime($subtrahend);

	return Delta_Days($y1, $m1+1, $d1, $y2, $m2+1, $d2);
}

1;

__END__