#!/home/localperl/bin/perl

use strict;
use warnings;

my @input_numbers = (1, 2, 4, 8, 16, 32, 64);
my @odd_digit_sum = grep digit_sum_is_odd($_), @input_numbers;
print "@odd_digit_sum\n";

sub digit_sum_is_odd
{
    my $input = shift; # Can use $_ instead of shift
    print "\$input: $input\n";
    my @digits = split //, $input;
    my $sum;
    $sum += $_ for @digits;
    return $sum % 2;
}