Question

我想为每个元素和sub以及sub的sub设置id或索引，依此类推

<?php

    $data = array(
        array(
            'title' => 'a',
            'children' => array(
                array(
                    'title' => 'a-a',
                    'children' => array(
                        array(
                            'title' => 'a-a-a',
                            'children' => array(

                            )
                        )                
                    )
                ),
                array(
                    'title' => 'a-b',
                    'children' => array(

                    )
                )                        
            )
        ),
        array(
            'title' => 'b',
            'children' => array(

            )
        )
    );

?>

我正在寻找与递归一起使用的PHP代码或函数来添加索引键和数字（desc）这样的输出

<?php

    $data = array(
        array(
            'index' => 1,
            'children' => array(
                array(
                    'index' => 2,
                    'children' => array(
                        array(
                            'index' => 3,
                            'children' => array(

                            )
                        )                
                    )
                ),
                array(
                    'index' => 4,
                    'children' => array(

                    )
                )                        
            )
        ),
        array(
            'index' => 5,
            'children' => array(

            )
        )
    );

?>

Answer 1

曾几何时，有一项研究得出的结论是，年轻的padawan程序员在成为绝地高级程序员的过程中面临的最大挑战是：

[...]有三个主要的语义障碍使新手命令式程序员绊倒。他们是：


分配和顺序

递归 / iteration

并发

我第一次在Jeff Atwood的博客文章Separating Programming Sheep from Non-Programming Goats中遇到了这个理论，该论文基于科学论文：The camel has two humps (working title)

这是实现您想要的代码（减去仅{em>可视化步骤的echo次调用）：

function addIndexRecursive(&$data) {
    static $index = 0;
    echo "The index is: $index" . PHP_EOL;

    foreach ($data as &$item) {
        $index++;
        echo "The index was incremented: {$index}" . PHP_EOL;

        $item = array('index' => $index) + $item;
        echo "Add the index to the item with title: {$item['title']}" . PHP_EOL;

        if (count($item['children']) > 0) {
            echo "This item has children so call the index function" . PHP_EOL;
            addIndexRecursive($item['children'], $index);
        // this else branch is only for illustration  purposes only
        } else {
            echo "There are no children therefore I stop" . PHP_EOL;
        }
    }
}

所以请稍微剖析一下。

首先要注意的是：我pass the array by reference。这只是一个品味问题，我更喜欢直接修改数组而不是构建另一个副本。

static $index将帮助我跟踪当前索引，并且会在遇到每个项目时递增。让我们看看这个static做了什么样的黑魔法（根据Variable scope）：

静态变量仅存在于本地函数作用域中，但在程序执行离开此作用域时它不会丢失其值。

再次

foreach ($data as &$item)我希望元素通过引用传递，这样我就可以直接在循环中修改它们。

现在我们讨论了实现细节，让我们看看该函数的 back-trace 是什么：

addIndexRecursive was call and the index is: 0
The index was incremented: 1
Add the index to the item with title: a
This item has children so call the function
    addIndexRecursive was call and the index is: 1
    The index was incremented: 2
    Add the index to the item with title: a-a
    This item has children so call the function
        addIndexRecursive was call and the index is: 2
        The index was incremented: 3
        Add the index to the item with title: a-a-a
        There are no children therefore I stop
    The index was incremented: 4
    Add the index to the item with title: a-b
    There are no children therefore I stop
The index was incremented: 5
Add the index to the item with title: b
There are no children therefore I stop

你会继续遇到这类问题，所以越早掌握递归概念越好。

Answer 2

这是“嵌套数组”的示例，其中各个数组需要：

1) an entry to be added: 'index' => <incrementing number> where there is a 'children' entry in the array.
2) an entry to be removed where: 'title' exists in the array.

由于数组可以“嵌套”，因此“递归”是处理“数据”数组的最合适方式。

我发现更容易修改数组“就地”而不是构建'output'数组。因此'数组引用'（＆amp; $ arrayEntry）使用了很多。

我使用提供的测试数据并测试'required'数组和'indexed'数组在'结构'方面是相同的。

这是经过测试的代码：Windows XP上的PHP 5.3.18。的 Working code at: viper-7.com

完成工作的功能：

function addChildrenIndex(&$destData, &$idxNew) { foreach($destData as $currentKey => &$currentValue) { // pass be reference so i can amend it if (is_array($currentValue)) { // ensure is 'children' array if (isset($currentValue['children'])) { // add the 'index' entry $currentValue['index'] = $idxNew; $idxNew++; } if (isset($currentValue['title'])) { // remove the 'title' entry! unset($currentValue['title']); } // as it is an array we 'recurse' around it - always... addChildrenIndex($currentValue, $idxNew); } } }

驾驶密码：

$idxNew = 1; // starting index. // COPY the source data so i can test it later if required... $indexedData = $data; // output array addChildrenIndex($indexedData, $idxNew); // re-index the array 'in place' // echo 'Required Array: <pre>'; // print_r($requiredData); // echo '</pre>'; // echo 'OutputArray: <pre>'; // print_r($indexedData); // echo '</pre>'; // test array structures to contain same entries... var_dump($indexedData == $requiredData, 'ARE EQUAL?');

必需的测试数据：见问题

索引输出：

Array ( [0] => Array ( [children] => Array ( [0] => Array ( [children] => Array ( [0] => Array ( [children] => Array ( ) [index] => 3 ) ) [index] => 2 ) [1] => Array ( [children] => Array ( ) [index] => 4 ) ) [index] => 1 ) [1] => Array ( [children] => Array ( ) [index] => 5 ) )

为递归数组中的每个元素设置id

2 个答案: