Looking at your question (not the code), it seems you're complicating the issue. Try the following approach:
  1. If the start date is before 2007-05-01,
    1. Set the start date to 2007-05-01.
  2. If the end date is before 2008-04-30,
    1. Set the end date to 2008-04-30.
  3. Calculate the difference.

I don't know why you're using both DateTime and Date::Calc. Here's a solution that uses the former. 

my $format = DateTime::Format::Strptime->new(
    pattern   => '%Y-%m-%d %H:%M:%S',
    time_zone => 'local',
);

my $min_start = DateTime->new( year => 2007, month => 5, day => 1, tim
+e_zone => 'local' );
my $max_stop  = DateTime->new( year => 2008, month => 5, day => 1, tim
+e_zone => 'local' );

[download]
my $start = $format->parse_datetime(...);
my $stop  = $format->parse_datetime(...);

$start = $min_start if $start < $min_start;
$stop  = $max_stop  if $stop >= $max_stop;

my $dur = $start->delta_ms($stop);

printf("%d minutes and %d seconds\n", $dur->in_units(qw( minutes secon
+ds ));

[download]

In reply to Re: calculate date difference by ikegami
in thread calculate date difference by hujunsimon

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