bash-3.00$ php -f test.php
array(5) {
  ["a"]=>
  string(6) "abcdef"
  ["b"]=>
  int(123456)
  ["c"]=>
  array(2) {
    [0]=>
    string(4) "1234"
    [1]=>
    string(4) "5678"
  }
  ["d"]=>
  &array(1) {
    ["a"]=>
    string(1) "b"
  }
  ["e"]=>
  int(123456)
}
array(5) {
  ["a"]=>
  string(6) "abcdef"
  ["b"]=>
  int(123456)
  ["c"]=>
  array(2) {
    [0]=>
    string(4) "1234"
    [1]=>
    string(4) "5678"
  }
  ["d"]=>
  &array(1) {
    ["a"]=>
    string(1) "c"
  }
  ["e"]=>
  int(123456)
}