use strict;
use warnings;
use 5.010;

my @arr1 = ("1", "", "");
my @arr2 = ("", "3", "4");

for my $index (0 .. 2) {
    say int($arr1[$index]) + int($arr2[$index]);
}

--output:--
Argument "" isn't numeric in int at 2perl.pl line 9.
1
Argument "" isn't numeric in int at 2perl.pl line 9.
3
Argument "" isn't numeric in int at 2perl.pl line 9.
4