如何正确使用array_udiff（）？ [英] How do I use array_udiff() correctly?

问题描述

我有两个多维数组，它们看起来都像这样：

I have two multidimensional arrays that both look something like this:

Array
(
    [0] => Array (
         'id' => 3,
         'other' => 'some string',
         'timestamp' => 2000-01-01 00:00:00
    ),

    [1] => Array (
         'id' => 6,
         'other' => 'another string',
         'timestamp' => 1835-01-01 00:00:00
    )
)

我试图找到一种方法来找出哪些元素显示在一个数组中（ $ b ），但是没有另一个（ $ a ）以及是否有任何值更改的元素。如果 $ a 是：

I'm trying to find a way to figure out which elements show up in one array ($b), but not the other ($a) and if there are any elements with changed values. If $a is:

Array
(
    [0] => Array (
         'id' => 3,
         'other' => 'some string',
         'timestamp' => 2000-01-01 00:00:00
    )
)

和 $ b 是：

Array
(
    [0] => Array (
         'id' => 3,
         'other' => 'some string',
         'timestamp' => 2000-01-01 12:12:12
    ),

    [1] => Array (
         'id' => 4,
         'other' => 'some string',
         'timestamp' => 1900-01-01 01:12:23
    )
)

然后函数应返回：

Array
(
    [0] => Array (
         'id' => 3,
         'other' => 'some string',
         'timestamp' => 2000-01-01 12:12:12
    ),

    [1] => Array (
         'id' => 4,
         'other' => 'some string',
         'timestamp' => 1900-01-01 01:12:23
    )
)

因为 id = 3 的元素已更改（ timestamp 字段），而的元素已更改id = 4 是新的，不会出现在其他数组中。

because the element with id = 3 has been changed (the timestamp field) and the element with id = 4 is new and doesn't appear in the other array.

我一直在尝试使用 array_udiff ，但我仍然不知道它是如何工作的（它似乎先对两个数组进行排序，但是然后如何进行比较？）。 array_udiff 是正确的方法还是应该编写自定义函数？

I've been trying to do this with array_udiff, but I still don't know how it works (it seems to sort both arrays first, but then how does it do comparison?). Is array_udiff the proper method or should I write a custom function?

推荐答案

您可以使用 array_udiff 并定义自己的比较回调。我假设这两个数组的结构完全相同。

You can use array_udiff and define your own comparison callback. I assume that both arrays has exactly the same structure.

您可以定义自己的回调函数，如下所示：

You can define your own callback function as follow:

int comparison(Array $a, Array $b){
    if ($a['id']==$b['id'] && $a['other']==$b['other'] && $a['timestamp']==$b['timestamp']){
        return 0
    }else{
        return -1
    }
}

回调函数必须返回如果第一个参数小于第二个参数，则为负整数；正数（如果更大）；或0（等于）。然后，您可以返回不等于0的任何数字，以指示参数不同，如果相等则返回0。

The callback function must return a negative integer if first argument is less than the second; a positive number if it's bigger; or 0 if it's equal. Then, you can return any number different to 0 to indicate that the arguments are different and 0 if they are the equal.

最后，应调用 array_udiff 如下：

array_udiff($a, $b, 'comparison')

您将获得 $ a 在 $ b 中没有或不同的。

And you will get a list of the elements of $a which are not, or are different in $b.

请注意，如果要比较2个数组当其中一个元素比另一个元素多时，应将包含新元素的数组作为第一个参数传递。

Note that if you want to compare 2 array when one of then has more elements than the other, you should pass as first argument the array with the new elements.

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