use strict;
use warnings;

sub testing(\@) {
   my ($arg) = @_;
   print("First argument: ", $arg, "\n");
   $arg->[5] = 'e';
}

my @a = qw( a b c d );

print("Test 1:\n");
testing(@a);
print("\n");

print("Test 2:\n");
&testing(@a);
print("\n");

__END__
output
======
Test 1:
First argument: ARRAY(0x1ab2780)

Test 2:
First argument: a
Can't use string ("a") as an ARRAY ref while "strict refs" in use at !.pl line 8
.