我怎样才能改变我的数组，直接影响我的foreach循环？ [英] How can I change my array, which directly affects my foreach loop?

问题描述

我使用foreach循环遍历一个数组。然而，在foreach循环中，我需要修改数组，以便它直接影响我的foreach循环。

所以我将举一个例子来解释我的问题：

pre $ <？php

$ array = [Red，Yellow，Blue，Orange ];
$ b foreach（$ array as $ color）{
if（（$ key = array_search（Blue，$ array））！== false）
unset（$ array [$键]）;

echo $ color。 <峰; br> 中;

}

？>


输出：

红色
黄色
 蓝色 
橙色
 

所以你可以看到我 unset（）值为 Blue 的数组元素。但我仍然在我的输出中。

现在我的问题是：如何取消设置值蓝色直接影响我的foreach循环，意味着我不会在输出中看到它，因为我在之前删除了我遍历该特定元素。



预期的输出是（注意：蓝色不在输出中）：



  Red 
 Yellow 
 Orange 
  




解决方案

您可以通过引用另一个变量来分配数组，这样 is_ref 是1，意味着foreach循环不会遍历数组副本。

所以，只要把它放在你的foreach循环之前就可以了：

  $ arr =& $ array; 
  

有关更多信息，请参阅： PHP的foreach实际上是如何工作的？

另外请注意，因为有一些PHP 7中的更改： http://php.net/manual /en/migration70.incompatible.php#migration70.incompatible.foreach 这将不再适用于PHP 7。

如果你想要做同样的事情在PHP 7中的行为改变只是说，你要通过引用循环访问数组，例如

  foreach（$ array as& $ color）
  

I loop through an array, which I have, using a foreach loop. However within the foreach loop I need to modify the array, so that it directly affects my foreach loop.

So I will make an example of my problem:

<?php

    $array = ["Red", "Yellow", "Blue", "Orange"];

    foreach($array as $color) {
        if(($key = array_search("Blue", $array)) !== false) 
            unset($array[$key]);

        echo $color . "<br>";

    }

?>

output:

Red
Yellow
Blue
Orange

So as you can see I unset() the array element with the value Blue. But I still have it in my output.

Now my question is: How can I unset the element with the value Blue, so that it directly affects my foreach loop, means I won't see it anymore in the output, since I deleted it before I loop over that specific element.

Expected output would be (Note: Blue is not in the output):

Red
Yellow
Orange

解决方案

You could assign your array by reference to another variable, so that is_ref is 1, means the foreach loop doesn't loop over a copy of your array anymore.

So just put this before your foreach loop:

$arr = &$array;

For more information how foreach actually works see: How does PHP 'foreach' actually work?

Also note, since there are some changes in PHP 7: http://php.net/manual/en/migration70.incompatible.php#migration70.incompatible.foreach this won't work anymore in PHP 7.

If you want to do the same in PHP 7 where the behavior is changed just say that you want to loop through the array by reference, e.g.

foreach($array as &$color)

这篇关于我怎样才能改变我的数组，直接影响我的foreach循环？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！