Assuming $hour is 0..23 initially, 
my $T;
for my $hour (0..23) {
   print "in: $hour ";
   if ($hour > 11) {
      $T = 'PM';
   } else {
      $T = 'AM';
   }
   ($hour %= 12) ||= 12;
   print "out: $hour $T\n";
}
__END__
in: 0 out: 12 AM
in: 1 out: 1 AM
in: 2 out: 2 AM
in: 3 out: 3 AM
in: 4 out: 4 AM
in: 5 out: 5 AM
in: 6 out: 6 AM
in: 7 out: 7 AM
in: 8 out: 8 AM
in: 9 out: 9 AM
in: 10 out: 10 AM
in: 11 out: 11 AM
in: 12 out: 12 PM
in: 13 out: 1 PM
in: 14 out: 2 PM
in: 15 out: 3 PM
in: 16 out: 4 PM
in: 17 out: 5 PM
in: 18 out: 6 PM
in: 19 out: 7 PM
in: 20 out: 8 PM
in: 21 out: 9 PM
in: 22 out: 10 PM
in: 23 out: 11 PM

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In reply to Re: Basic programming question by ysth
in thread Basic programming question by j.goor

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