# Using hard references
my @cat = (1,2,3);
my @dog = (5,6);
my @pig = (4,3,2,1);
for my $array (\@cat, \@dog, \@pig) {
    # On first iteration $array will contain a reference to @cat.
    # On second iteration, $array will contain a reference to @dog.
    # On third iteration $array will contain a reference to @pig.
}