use strict;
use warnings;
use DateTime;
use IO::Prompt::Tiny qw( prompt );

# Get a DateTime object for birthday and now based on user input.
my( $bday, $now ) = map {
  print "$_ date entry:\n";
  DateTime->new( map { $_ => prompt "\tPlease enter $_:" } qw(day month year) )
} qw(Birth Today's);

die "Birth date must be in the past.\n" unless $bday < $now;

# Perform the math.
print "\nYou are ", $bday->delta_days($now)->in_units('days'), " days old.\n";