my @array = qw/one two three four five/;
print scalar @array;
__OUTPUT__
5

##</code><code>##

my @array = qw/one two three four five/;
print $#array;
__OUTPUT__
4

##</code><code>##

my @array = qw/one two three four five/;
$array[2] = undef;  # undefine one of the elements.
print scalar grep { defined $_ } @array;
__OUTPUT__
4

##</code><code>##

my @array = qw/one two three four five/;
print $array[-1];
__OUTPUT__
five

##</code><code>##

my @array = qw/one two three four five/;
$#array = 99;
print scalar @array;
__OUTPUT__
100