or download this
@a = qw(a b c d e); # Array has 5 elements, with room for 10;
push(@a, qw(f g h i j)); # Array has ten elements, with room for 10.
...
push(@a, qw(u v w x y)); # Array has 25 elements with room for 30.
push(@a, qw(z 1 2 3 4)); # Array has 30 elements with room for 30.
push(@a, qw(5 6 7 8 9)); # Array has to be moved to new memory. Array
+has 35 elements with room for 70.