#!/usr/bin/perl
use 5.014;       # functional equiv to use strict; use warnings; for this demo
# 985557

my ($x, @array, $index, $arr_ref, @arr);

sub sub1{
    for $x (0 .. 3){
	$array[$x] = 0;
    }
    say "\t from sub \$array[\$x]: |$array[$x]|";

# omit the part for generating the array;

    return \@array;
}

####################### main part

for ($index=0; $index<2; $index++){
    $arr_ref = &sub1($index);
    $arr[$index] = @$arr_ref;

    foreach $_ (0 .. 3){
        say "\@arr | @arr |, \$index: |$index|, \$_: |@_|";
	   # print "$arr[$index][$_]\n"; 
       # Can't use string ("101") as an ARRAY ref while "strict refs" 
       # in use at 985557.pl line 24.
    }
    say "\@arr | @arr |, \$index: |$index|, \$_: |@_|";
}
say "\@arr | @arr |, \$index: |$index|, \$_: |@_|";