In addition, you have trouble brewing once you fix that problem. You are defining your $months hash as a hash reference instead of a hash, and that breaks in the loop that follows. The relevant part of you code (with corrections) is: 

  my %months = (        ## Change $ to %  and { to (   --- no reason t
+o use a reference here.
         'JAN'  => '31',
         'FEB'  => "$feb",
         'MAR'  => '31',
         'APR'  => '30',
         'MAY'  => '31',
         'JUN'  => '30',
         'JUL'  => '31',
         'AUG'  => '31',
         'SEP'  => '30',
         'OCT' => '31',
         'NOV' => '30',
         'DEC' => '31',
        );                ## Changed {  to )
  my @month_keys = (keys %months);
  my $tot_days = $dd;
  for (my $i = 0; $month_keys[$i] ne $mon; $i++) { # Added my

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Also, in future, it is better to ask your questions in the Seeker of Perl Wisdom section rather than here in the Q&A section. This is reserved for generic Q&A's, rather than specific questions like your.

In reply to Re: Why does my subroutine not receive the scalar parameter as $_? by BrowserUk
in thread Why does my subroutine not receive the scalar parameter as $_? by @ncientgoose

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