You could try doing this:

use warnings;
use strict;

my @array1=(1, 2, 0);
my @array2=(1, 1, 1);

sub addarrays {
 my ($a1, $a2) = @_;
 @$a2=@$a1+@$a2;
}

addarrays(\@array1, \@array2);
print @array2;
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Warnings: Perl monks may behave like satinists, but only when (@{[localtime]})==9.