@animals = qw(cat dog bat rat gerbil snake pig chicken);

  foreach (@animals) { $animals{$_}++; }  # initialize %animals hash

  # use a hash
  if (exists $animals{'pig'}) {
    print "We have a pig!\n";
  }  

  # use grep
  if (grep { $_ eq 'snake'} @animals) {
    print "We have a snake!\n";
  }

  # use a for loop
  for (@animals) {
    last if $_ eq 'dog';
  }
  print "We have a dog!\n";