我应该如何解决这阵与usort键？

问题描述

我想我可能已经阅读每 usort StackOverflow上的文章，但我不能工作了这一个。这可能是 usort 不是工具，我需要什么？下面是一个数组的一点是我的工作（我把它分配给 $所有页）

I think I might have read every usort article on StackOverflow, but I can't work out this one. It might be that usort is not the tool I need? Here's a bit of the array that I'm working with (I have it assigned to $allPages):

Array
(
    [0] => Page Object
        (
            [id] => 4
            [slug] => articles
            [created_on] => 2009-08-06 07:16:00
        )

    [1] => Page Object
        (
            [id] => 99
            [slug] => a-brief-history
            [created_on] => 2011-04-25 12:07:26
        )

    [2] => Page Object
        (
            [id] => 98
            [slug] => we-arrive
            [created_on] => 2011-04-24 13:52:35
        )

    [3] => Page Object
        (
            [id] => 83
            [slug] => new-year
            [created_on] => 2011-01-02 14:05:12
        )
)

我想最终排序的 created_on 价值，但就目前而言，我对能够排序其中的任何解决！当我尝试正常 CMP（$ A，$ B）与 usort 键入回调 - ，例如，在this回答一个问题usort - 我只是得到了一个空白。例如：

I am trying ultimately to sort on the created_on value, but for the moment, I'd settle on being able to sort on any of them! When I try the normal cmp($a, $b) type callback with usort -- as, for example, in this answer on a usort question -- I just get a blank. Example:

function cmp($a, $b) {
  return strcmp($a["slug"], $b["slug"]);
}
usort($allPages, 'cmp')

和的print_r 给我什么。这是用PHP 5.2.n，而不是5.3 BTW。

And print_r gives me nothing. This is with PHP 5.2.n, not 5.3 btw.

指导，好吗？和Thankyou！

Guidance, please? And thankyou!

推荐答案

您数组中的项目对象，而不是关联数组，所以你需要参考他们这样的：

Your items in the array are objects, not associative arrays, so you need to refer to them like this:

function cmp($a, $b) {
  return strcmp($a->slug, $b->slug);
}
usort($allPages, 'cmp')

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