按子值排序父数组答案

【问题标题】：Sort Parent array by child value按子值排序父数组
【发布时间】：2010-11-22 01:30:09
【问题描述】：

如何按任何子值（即：post_id、用户名等）对以下数组进行排序？

Array(
[0] => Array
    (
        [id] => 10
        [post_id] => 398
        [user_id] => 0
        [view_date] => 2010-11-20 15:26:00
        [views] => 4
        [username] => <em>guest</em> 
    )

[1] => Array
    (
        [id] => 9
        [post_id] => 397
        [user_id] => 1
        [view_date] => 2010-11-19 23:35:39
        [views] => 1
        [username] => Fire G
    )

[2] => Array
    (
        [id] => 8
        [post_id] => 398
        [user_id] => 1
        [view_date] => 2010-11-19 23:35:26
        [views] => 4
        [username] => Fire G
    )

[3] => Array
    (
        [id] => 7
        [post_id] => 396
        [user_id] => 1
        [view_date] => 2010-11-19 23:07:57
        [views] => 3
        [username] => Fire G
    )

[4] => Array
    (
        [id] => 6
        [post_id] => 396
        [user_id] => 1
        [view_date] => 2010-11-19 23:07:55
        [views] => 3
        [username] => Fire G
    )

[5] => Array
    (
        [id] => 5
        [post_id] => 396
        [user_id] => 1
        [view_date] => 2010-11-19 23:07:52
        [views] => 3
        [username] => Fire G
    )

[6] => Array
    (
        [id] => 4
        [post_id] => 13
        [user_id] => 1
        [view_date] => 2010-11-19 22:59:35
        [views] => 1
        [username] => Fire G
    )

[7] => Array
    (
        [id] => 3
        [post_id] => 3
        [user_id] => 1
        [view_date] => 2010-11-19 22:59:28
        [views] => 1
        [username] => Fire G
    )

[8] => Array
    (
        [id] => 2
        [post_id] => 398
        [user_id] => 1
        [view_date] => 2010-11-18 11:37:20
        [views] => 4
        [username] => Fire G
    )

[9] => Array
    (
        [id] => 1
        [post_id] => 398
        [user_id] => 1
        [view_date] => 2010-11-18 11:37:16
        [views] => 4
        [username] => Fire G
    )
)

【问题讨论】：

标签： php arrays multidimensional-array sorting

【解决方案1】：

使用uasort，用户定义的排序，让您可以提供自己的函数来定义一个元素是否应该排在另一个之前。

http://www.php.net/manual/en/function.uasort.php

您的比较器功能类似于

function cmp($a, $b) {
    return $a['post_id'] > $b['post_id'] ? 1 : -1;
}

【讨论】：

我不知道那是什么意思。帖子 ID 之间的代数差异？
@Dan Grossman 对不起，我的意思是如果你返回一个减去另一个，如果它们不同，它将给出负数或正数，如果它们相同，则为 0。有效满足排序回调的要求。
字母比较呢？
他们呢？如果您比较字符串，PHP 将使用字典顺序。 “狗”>“猫”。如果您想要其他类型的排序，只需再次定义您自己的比较函数。
很有帮助，一直在找这个