Start by not hiding/ignoring warnings

Scalar value @start_date_array[0] better written as $start_date_array[
+0] at a.pl line 12.
Scalar value @today_date_array[0] better written as $today_date_array[
+0] at a.pl line 12.
Scalar value @start_date_array[1] better written as $start_date_array[
+1] at a.pl line 12.
Scalar value @today_date_array[1] better written as $today_date_array[
+1] at a.pl line 12.
Scalar value @start_date_array[2] better written as $start_date_array[
+2] at a.pl line 12.
Scalar value @today_date_array[2] better written as $today_date_array[
+2] at a.pl line 12.
Scalar value @end_date_array[0] better written as $end_date_array[0] a
+t a.pl line 14.
Scalar value @today_date_array[0] better written as $today_date_array[
+0] at a.pl line 14.
Scalar value @end_date_array[1] better written as $end_date_array[1] a
+t a.pl line 14.
Scalar value @today_date_array[1] better written as $today_date_array[
+1] at a.pl line 14.
Scalar value @end_date_array[2] better written as $end_date_array[2] a
+t a.pl line 14.
Scalar value @today_date_array[2] better written as $today_date_array[
+2] at a.pl line 14.
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Mind you, that warning doesn't indicate a real problem here (it points out a bad style/habit that can have an effect in uncommon circumstances), but who knows what other warnings are being issued. Add use warnings; if it's not already there.