usort 返回不可预测的结果答案

【问题标题】：usort returning unpredicable resultsusort 返回不可预测的结果
【发布时间】：2011-11-30 21:05:24
【问题描述】：

我有一个从数据库返回的对象数组。未排序数组上的 print_r 如下所示：

Array
(
    [0] => stdClass Object
        (
            [nid] => 53162
            [title] => Kroger &#039;Giving Hope&#039; Standee
            [path] => node/53162
        )

    [1] => stdClass Object
        (
            [nid] => 64185
            [title] => Kroger &#039;Giving Hope&#039; Stanchion Sign
            [path] => node/64185
        )

    [2] => stdClass Object
        (
            [nid] => 52190
            [title] => Betty Crocker Kroger &#039;Giving Hope&#039; Shipper
            [path] => node/52190
        )

    [3] => stdClass Object
        (
            [nid] => 53159
            [title] => Frito-Lay Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/53159
        )

    [4] => stdClass Object
        (
            [nid] => 53164
            [title] => Nabisco Kroger &#039;Giving Hope&#039; Violator
            [path] => node/53164
        )

    [5] => stdClass Object
        (
            [nid] => 52607
            [title] => Doritos Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/52607
        )

    [6] => stdClass Object
        (
            [nid] => 52720
            [title] => Kroger Big K Cola &#039;Giving Hope&#039; Packaging
            [path] => node/52720
        )

    [7] => stdClass Object
        (
            [nid] => 52729
            [title] => Windex Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/52729
        )

    [8] => stdClass Object
        (
            [nid] => 52731
            [title] => Ziploc Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/52731
        )

    [9] => stdClass Object
        (
            [nid] => 53157
            [title] => Stacy&#039;s Kroger &#039;Giving Hope&#039; Cut Cases
            [path] => node/53157
        )

)

我想通过nid属性对数组进行排序，所以我使用了自定义的usort函数（找到here。）

function my_search_sort($a, $b) {
  strcmp($a->nid, $b->nid);
}

我这样称呼它：

usort($docs, 'my_search_sort');

然后又做了一个 print_r。结果如下所示：

Array
(
    [0] => stdClass Object
        (
            [nid] => 52720
            [title] => Kroger Big K Cola &#039;Giving Hope&#039; Packaging
            [path] => node/52720
        )

    [1] => stdClass Object
        (
            [nid] => 52729
            [title] => Windex Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/52729
        )

    [2] => stdClass Object
        (
            [nid] => 52731
            [title] => Ziploc Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/52731
        )

    [3] => stdClass Object
        (
            [nid] => 53157
            [title] => Stacy&#039;s Kroger &#039;Giving Hope&#039; Cut Cases
            [path] => node/53157
        )

    [4] => stdClass Object
        (
            [nid] => 52607
            [title] => Doritos Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/52607
        )

    [5] => stdClass Object
        (
            [nid] => 53164
            [title] => Nabisco Kroger &#039;Giving Hope&#039; Violator
            [path] => node/53164
        )

    [6] => stdClass Object
        (
            [nid] => 64185
            [title] => Kroger &#039;Giving Hope&#039; Stanchion Sign
            [path] => node/64185
        )

    [7] => stdClass Object
        (
            [nid] => 52190
            [title] => Betty Crocker Kroger &#039;Giving Hope&#039; Shipper
            [path] => node/52190
        )

    [8] => stdClass Object
        (
            [nid] => 53159
            [title] => Frito-Lay Kroger &#039;Giving Hope&#039; Packaging
            [path] => node/53159
        )

    [9] => stdClass Object
        (
            [nid] => 53162
            [title] => Kroger &#039;Giving Hope&#039; Standee
            [path] => node/53162
        )

)

它显然是在做something，但它并没有按照nid 升序排序。我需要做什么才能让它发挥作用？

【问题讨论】：

标签： php multidimensional-array sorting usort

【解决方案1】：

你的自定义排序函数需要返回值：

function my_search_sort($a, $b) {
  return strcmp($a->nid, $b->nid);
}

编辑我更新了other answer you referenced上的代码，不正确。

【讨论】：