<p>Program testing how arrays work:</p>
array(1) {
  [1]=>
  string(1) "d"
}

array(4) {
  ["foo"]=>
  string(3) "bar"
  ["bar"]=>
  string(3) "foo"
  [100]=>
  int(-100)
  [-100]=>
  int(100)
}

array(4) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
  [33]=>
  string(5) "hello"
  [34]=>
  int(34)
}
<p>How to access array elements:</p>
string(3) "bar"
int(24)
array(1) {
  ["dimensional"]=>
  array(1) {
    ["array"]=>
    string(3) "foo"
  }
}
array(1) {
  ["array"]=>
  string(3) "foo"
}
string(3) "foo"

array(3) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
}
int(2)
int(2)
<p>Creating/modifying arrays with square bracket syntax:</p>
array(2) {
  [5]=>
  int(1)
  [12]=>
  int(2)
}
array(3) {
  [5]=>
  int(1)
  [12]=>
  int(2)
  [13]=>
  int(56)
}
array(4) {
  [5]=>
  int(1)
  [12]=>
  int(2)
  [13]=>
  int(56)
  ["x"]=>
  int(42)
}
array(3) {
  [5]=>
  int(1)
  [13]=>
  int(56)
  ["x"]=>
  int(42)
}
NULL
<p>Copy an array by value or by reference:</p>
array(2) {
  [0]=>
  int(2)
  [1]=>
  int(3)
}
array(3) {
  [0]=>
  int(2)
  [1]=>
  int(3)
  [2]=>
  int(4)
}
array(3) {
  [0]=>
  int(2)
  [1]=>
  int(3)
  [2]=>
  int(4)
}
array(3) {
  [0]=>
  int(2)
  [1]=>
  int(3)
  [2]=>
  int(4)
}