#!/usr/bin/perl -lw
use strict;

my $a = 1;
my $b = 2;

sub swap {
  my @in = \( @_ ); # create our references, although pointless here
  ${$in[0]}^=${$in[1]};${$in[1]}^=${$in[0]};${$in[0]}^=${$in[1]};
}

print "$a $b";
swap($a,$b);
print "$a $b";
__DATA__
output:
1 2
2 1

##</code><code>##

#!/usr/bin/perl -wl
use strict;

my @a = qw(a b c x);
my @b = qw(d e f y);
my %c = qw(g h i j);
my $d = "bill";

sub array_and_array {
  my (@z,@y) = @_;
  print "z: @z | y: @y";
}

sub hash_and_array {
  my (%x,@w) = @_;
  local $, = $"; # just so we can print out %x
  print "x:",%x,"| w: @w";
}

sub array_and_scalar {
  my (@v,$u) = @_;
  print "v: @v | u: ",$u?$u:"";
}

sub scalar_and_array {
  my ($t,@s) = @_;
  print "t: $t | s: @s";
}

sub know_length_arrays {
  my (@r,@q);
  (@r[0..3],@q[0..3]) = @_;
  print "r: @r | q: @q";
}

sub know_length_array_with_hash {
  my (@p,%o);
  (@p[0..3],%o) = @_;
  local $, = $";
  print "p: @p | o:",%o;
}

array_and_array(@a,@b);
hash_and_array(%c,@a);
array_and_scalar(@a,$d);
scalar_and_array($d,@a);
know_length(@a,@b);
know_length_array_with_hash(@a,%c);

__DATA__
output:
z: a b c x d e f y | y:
x: c x a b g h i j | w:
v: a b c x bill | u:
t: bill | s: a b c x
r: a b c x | q: d e f y
p: a b c x | o: g h i j