1

     'aaa',];$arr2 = $arr;$arr2['a'] = 'ccc';print_r($arr);print_r($arr2);// Array// (//     [a] => aaa// )// Array// (//     [a] => ccc// )// ==========function foo($array) {    $array['a'] = 'ddd';}foo($arr);print_r($arr);// Array// (//     [a] => aaa// )// ==========function bar(&$array) {    $array['a'] = 'eee';}bar($arr);print_r($arr);// Array// (//     [a] => eee// )?>

2

    p = 'bbb';print_r($c);print_r($c2);// C Object// (//     [p] => bbb// )// C Object// (//     [p] => bbb// )$c3 = &$c;$c = null;var_dump($c);var_dump($c2);var_dump($c3);// NULL// object(C)#1 (1) {//   ["p"]=>//   string(3) "bbb"// }// NULL?>

3