了解array_udiff（） [英] Understanding array_udiff()

问题描述

我有以下简单的功能，试图了解 array_udiff（）函数

I have the following simple function to try and understand the array_udiff() function

function udiffCompare( $value, $value2 )
{

echo $value . " - " . $value2 . "<br />";

}

$newArray   =   array(  

                    'value2' => 2, 
                    'value3' => 3, 
                    'value4' => 4
                );

$newArray2  =   array(  

                    'value2' => 2, 
                    'value3' => 3, 
                    'value4' => 4
                );

array_udiff( $newArray, $newArray2, 'udiffCompare' );

我希望这只是返回：

I would expect this to simply return:

2 - 2
3 - 3
4 - 4

然而，它返回：

3 - 2
4 - 3
3 - 2
4 - 3
4 - 4
4 - 3
4 - 3
3 - 2

这使我相信有些事情我真的不理解这里如何 array_udiff（）的作品。

This leads me to believe there is something I am really not understanding here about how array_udiff() works.

即使我将其替换上面的echo语句：

Even if I replace the echo statement above with:

如果（$价值== $值2）{返回1; }其他{返回0; }

输出的阵列完全是空的，即使传递给函数的所有值都是平等的。

the outputted array is completely empty even though all the values passed to the function are equal.

有人能照亮一盏灯吗？

推荐答案

array_udiff 计算的区别的两个阵列。这是 $ newArray 所有条目，不能在 $ newArray2 。在这种情况下，结果是一个空数组，因为没有差别。

array_udiff computes the difference of the two arrays. That is all entries in $newArray which are not in $newArray2. In this case the result is an empty array because there is no difference.

您所看到的输出是因为你呼应正在被比较的每个值。究其原因，这是一个大的名单是因为，为了找出差异 array_udiff 的每一个值 $ newArray 与 $ newArray2 的每个值。

The output you are seeing is because you are echoing each value that is being compared. The reason this is a larger list is because, in order to find out the difference array_udiff has to compare every value in $newArray with every value in $newArray2.

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