php树形结构显示

Question

php结构前端

Answer 1

$a = array(array(7,5),array(7,6,1),array(7,6,2,3,5),array(7,6,2,3,6));$root = array();
foreach($a as $item) {
  $p =& $root;
  foreach($item as $k) {
    if(!isset($p[$k])) $p[$k] = array();
    $p =& $p[$k];
  }
}
print_r($root);
Array
(
    [7] => Array
        (
            [5] => Array
                (
                )            [6] => Array
                (
                    [1] => Array
                        (
                        )                    [2] => Array
                        (
                            [3] => Array
                                (
                                    [5] => Array
                                        (
                                        )                                    [6] => Array
                                        (
                                        )                                )                        )                )        ))

Answer 2

$p =& $p[$k]; 这句话是什么意思？看不懂

Answer 3

&应该是指 引用。
$p =& $p[$k]; 
是把 $p[$k]指向的内存地址 赋值给了$p有点类似指针。如果不用 & 的话。会很麻烦。