PHP 该多维数组如何递归循环？

Question

$arr = [
    [
        'id' => 1,
        'children' => [
            'id' => 2,
            'children' => [
                'id' => 3,
                'children' => [
                    'id' => 4
                ]
            ]
        ]
    ],
    [
        'id' => 5,
        'children' => [
            'id' => 6,
        ]
    ],
    [
        'id' => 7
    ]
];

存在children数组则将children数组里的id赋值给新的数组，最终组成新的数组如下：

$arr2 = [
    [1,2,3,4],
    [5,6],
    [7]
];

Answer 1

<?php


$arr = [
    [
        'id' => 1,
        'children' => [
            'id' => 2,
            'children' => [
                'id' => 3,
                'children' => [
                    'id' => 4
                ]
            ]
        ]
    ],
    [
        'id' => 5,
        'children' => [
            'id' => 6,
        ]
    ],
    [
        'id' => 7
    ]
];

function pushChild($children, &$container) 
{
    $container[] = $children['id'];
    if (! isset($children['children'])) {
        return;
    }
    pushChild($children['children'], $container);
}

$arr2 = [];

foreach ($arr as $item) {
    $result = [];
    pushChild($item, $result);
    $arr2[] = $result;
}

var_dump($arr2);

输出

~ ❯❯❯ php test.php
array(3) {
  [0]=>
  array(4) {
    [0]=>
    int(1)
    [1]=>
    int(2)
    [2]=>
    int(3)
    [3]=>
    int(4)
  }
  [1]=>
  array(2) {
    [0]=>
    int(5)
    [1]=>
    int(6)
  }
  [2]=>
  array(1) {
    [0]=>
    int(7)
  }
}

Answer 2

    $data = new \RecursiveArrayIterator($data);
    $iterator = new \RecursiveIteratorIterator($data,\RecursiveIteratorIterator::SELF_FIRST);
    $iteratorArr = [];
    foreach ($iterator as $key=>$element) {
    }

试试RecursiveArrayIterator递归