#!/usr/bin/env perl
use strict;
use warnings;
use Data::Dumper;

my $arr=[1,2,3];
$arr[1] = 12;           # Global symbol "@arr" requires explicit package name (did you forget to declare "my @arr"?)

my $y = {a=>1,b=>2};
$y['c'] = 3;            # Global symbol "@y" requires explicit package name (did you forget to declare "my @y"?)

print Data::Dumper->Dump([$arr, $y], [qw/arr y/]);
__END__
Global symbol "@arr" requires explicit package name (did you forget to declare "my @arr"?) at C:\usr\local\share\PassThru\perl\perlmonks\11116710.pl line 7.
Global symbol "@y" requires explicit package name (did you forget to declare "my @y"?) at C:\usr\local\share\PassThru\perl\perlmonks\11116710.pl line 10.
Execution of C:\usr\local\share\PassThru\perl\perlmonks\11116710.pl aborted due to compilation errors.