如何删除数组中除特定项目以外的所有项目? [英] How to remove all items of array except specific one?

问题描述

我有一个包含这些嵌套数组的变量:

I have a variable which is containing these nested arrays:

echo $var;

/* Output:
Array(
       [0] => Array
         (
             [id] => 1
             [box] => 0
         )

       [2] => Array
         (
             [id] => 2
             [box] => 0
         )

       [3] => Array
         (
             [id] => 3
             [box] => 1
         )
) */

现在，我想删除上面数组中除 $ numb = 2; (id的值)以外的所有项.我的意思是我想要这个输出:

Now I want to remove all items of array above except $numb = 2; (the value of id). I mean I want this output:

echo newvar;

/* Output:
Array(
       [2] => Array
         (
             [id] => 2
             [box] => 0
         )
) */

我该怎么做?

实际上，我可以使用 if 语句和 array_shift()函数来完成其中的一部分:

Actually I can do a part of it by using if statement and array_shift() function:

foreach($var as $key => $val) {
    if($val["id"] != 2) {
        array_shift($var);
    }
}

但是上面的代码输出不需要我.

But the output of code above isn't want I need.

推荐答案

您可以使用略有不同的循环.

You can use a slightly different loop.

foreach ($var as $item) {
    if ($item['id'] == 2) {
        $newvar = $item;
        break;
    }
}

您还可以使用array_filter

You could also use array_filter

$id = 2;
$newvar = array_filter($var, function($x) use ($id) { return $x['id'] == $id; });

但是它很可能效率较低，因为它必须检查数组的每个元素.

but it would most likely be less efficient as it would have to check every element of the array.

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