#!/usr/bin/perl -w
use strict;
use warnings;

sub add {
        my ($first, @rest) = @_;

        if (!defined $first) {
                0;
        }
        else {
                die "operand may not be negative!" unless $first >= 0;
                if ($first == 0) {
                        add(@rest);
                }
                else {
                        1 + add($first-1, @rest);
                }
        }
}

sub print_add {
        print join(" + ", @_), " = ", add(@_), "\n";
}

print_add 2,2;
print_add 2,2,2;
print_add 4,8,12;


##</code><code>##

root@swill ~/PerlMonks
$ ./adder_1.pl
2 + 2 = 4
2 + 2 + 2 = 6
4 + 8 + 12 = 24


##</code><code>##

sub add {
        my $accumulator = 0;
        for my $op (@_) {
                for my $i (1 .. $op) {
                        $accumulator = $accumulator+1;
                }
        }
        $accumulator;
}


##</code><code>##

#!/usr/bin/perl -w
use strict;
use warnings;

use Benchmark qw(timethese cmpthese);

sub add_rec {
        my ($first, @rest) = @_;


        if (!defined $first) {
                0;
        }
        else {
                die "operand may not be negative!" unless $first >= 0;
                if ($first == 0) {
                        add_rec(@rest);
                }
                else {
                        1 + add_rec($first-1, @rest);
                }
        }
}

sub add_iter {
        my $accumulator = 0;
        for my $op (@_) {
                for my $i (1 .. $op) {
                        $accumulator = $accumulator+1;
                }
        }
        $accumulator;
}

cmpthese(100000, {
        'Recursive' => sub { 2 == add_rec(2,2); },
        'Iterative' => sub { 2 == add_iter(2,2); }
});


##</code><code>##

$ ./adder_bench.pl
              Rate Recursive Iterative
Recursive  79051/s        --      -48%
Iterative 152207/s       93%        --