use Time::Piece;   # Core module
use Time::Seconds; # Core module

use constant TIME_FORMAT => '%I:%M%p';

my( $starttime, $endtime, $currenttime ) = 
  ( '9:01PM',   '3:30AM', '1:10AM'     );

# Create Time::Piece objects

my( $st, $et, $ct ) = map {
  Time::Piece->strptime( $_, TIME_FORMAT );
} ( $starttime, $endtime, $currenttime );



# Coerce end time to always be after start time.
# Coerce current time to always fall after start time (because time without
# date is ambiguous)

( $et, $ct ) = map { $_ < $st ? $_ + ONE_DAY : $_ } ( $et, $ct );


# Now we don't technically need to verify that $ct >= $st, but semantically it
# doesn't hurt, and probably aids understanding of the algorithm, in case
# one wants to deal with the ambiguity of a missing date differently.

print $ct->strftime(TIME_FORMAT), " is ",
      ( $ct >= $st && $ct <= $et ) ? "in" : "out of",
      " range\n";