$[ = -4;
@a = (qw(a b c d e f g h i j));
print $a[-1], "\n";
print $a[$#a], "\n";
__DATA__
d
j

##</code><code>##

$[ = 0;
@a = (qw(a b c d e f g h i j));
print $a[-1], "\n";
print $a[$#a], "\n";
__DATA__
j
j

##</code><code>##

for x in 100 1 0 -1 -6 -7 -11 -12 -99; do
    perl -le "\$[=$x; my @ra=qw(a b c d e f); print \$[, ': -1:' , \$ra[-1], ': $#: ', \$ra[\$#ra]"
done

##</code><code>##

100: -1: f: $#: f
1: -1: f: $#: f
0: -1: f: $#: f
-1: -1: f: $#: f
-6: -1: f: $#: f
-7: -1: f: $#: e
-11: -1: f: $#: a
-12: -1: f: $#: 
-99: -1: f: $#: 

##</code><code>##

100: -1: f: $#: f
1: -1: f: $#: f
0: -1: f: $#: f
-1: -1: a: $#: f
-6: -1: f: $#: f
-7: -1: : $#: e
-11: -1: : $#: a
-12: -1: : $#: 
-99: -1: : $#: