按特定键对多维数组进行递归排序

Question

我试图通过其标签递归地对此数组进行排序：

Array
(
    [0] => Array
        (
            [id] => 6
            [label] => Bontakt
            [children] => Array
                (
                )

        )

    [1] => Array
        (
            [id] => 7
            [label] => Ampressum
            [children] => Array
                (
                    [0] => Array
                        (
                            [id] => 5
                            [children] => Array
                                (
                                )

                            [label] => Bome
                        )

                    [1] => Array
                        (
                            [id] => 8
                            [children] => Array
                                (
                                )

                            [label] => Aome
                        )

                    [2] => Array
                        (
                            [id] => 10
                            [children] => Array
                                (
                                )

                            [label] => Come
                        )

                )

        )

    [2] => Array
        (
            [id] => 9
            [label] => Contakt
            [children] => Array
                (
                )

        )

    [3] => Array
        (
            [id] => 11
            [label] => Dead
            [children] => Array
                (
                )

        )

)

我已经阅读了几个问题，我觉得非常接近，但我无法弄清楚哪些问题无效：

function sortByAlpha($a, $b)
{
    return strcmp(strtolower($a['label']), strtolower($b['label'])) > 0;
}

function alphaSort(&$a)
{
    foreach ($a as $oneJsonSite)
    {
        if (count($oneJsonSite["children"]) > 0) alphaSort($oneJsonSite["children"]);
    }

    usort($a, 'sortByAlpha');
}


alphaSort($jsonSites);

当前输出是这样的：

Ampressum
    Bome
    Aome
    Come
Bontakt
Contakt
Dead

子元素未排序......

Answer 1

检查出来：

为了能够直接修改循环中的数组元素，在$ value之前加上＆amp ;.在这种情况下，该值将通过引用分配。 （从这里挑选：http://php.net/manual/en/control-structures.foreach.php）

你应该试试这个：

function alphaSort(&$a)
{
    foreach ($a as &$oneJsonSite)
    {
        if (count($oneJsonSite["children"]) > 0) alphaSort($oneJsonSite["children"]);
    }

    usort($a, 'sortByAlpha');
}