use strict;
use Benchmark;

my ($x,$i);

my @f = ('a'..'zz');
my $f = \@f;

sub first_one {
  for (@f) {$x++}
}
sub second_one {
  for (@$f) {$x++}
}
sub third_one {
  for ('a'..'zz') {$x++}
}
sub fourth_one {
  for ($i=0;$i<=$#f;$i++) {$x++}
}

timethese(10_000, {
    'first' => \&first_one,
    'second' => \&second_one,
    'third' => \&third_one,
    'fourth' => \&fourth_one,
});

##</code><code>##

Benchmark: timing 10000 iterations of first, fourth, second, third...
     first:  6 wallclock secs ( 6.02 usr +  0.00 sys =  6.02 CPU) @ 1661.68/s (n=10000)
    fourth: 12 wallclock secs (11.98 usr +  0.00 sys = 11.98 CPU) @ 834.86/s (n=10000)
    second:  7 wallclock secs ( 6.00 usr +  0.00 sys =  6.00 CPU) @ 1667.22/s (n=10000)
     third:  9 wallclock secs ( 9.57 usr +  0.00 sys =  9.57 CPU) @ 1044.50/s (n=10000)