use warnings;
use strict;

my @array = (1,2,3,4,5);
my $v = 1;

sub by_ref 
{
    my ($array_ref,$v) = @_;  
    @$array_ref = (0,0,0);
    print "Array inside by_ref: @$array_ref\n"; 
}

by_ref(\@array,$v);
print "Array changed: @array\n";