use strict;
use Benchmark;
use Inline 'C';

my $top = 150;

timethese(500000,
      {
       recursive_perl => sub {factorial_recursive_perl($top)},
       iterative_perl => sub {factorial_iterative_perl($top)},
       recursive_c    => sub {factorial_recursive_c(   $top)},
       iterative_c    => sub {factorial_iterative_c(   $top)},
      });

sub factorial_recursive_perl {
    return 1 if $_[0] < 2;
    return $_[0] * factorial_recursive_perl($_[0] - 1);
}

sub factorial_iterative_perl {
    my $return = 1;
    $return *= $_ for 2..$_[0];
    return $return;
}

__END__

__C__

double factorial_recursive_c(int x) {
    if (x < 2)  return 1;
    return x * factorial_recursive_c(x - 1);
}

double factorial_iterative_c(int x) {
    int i;
    double result = 1;
    for (i = 2; i <= x; i++) result *= i;
    return result;
}