問(wèn)題描述

我有一個(gè)非常基本的問(wèn)題，但我被卡住了.我對(duì) php 很陌生，我有一個(gè)這樣的數(shù)組:

I have a pretty basic question but I am stuck. I am pretty new to php and I have an array like this:

$array = array(
    'one' => 1,
    'two' => array('key1' => 'val1','key2' => 'val2'),
    'three' => array('key1' => 'val1','key2' => 'val2'),
    'four' => array('key1' => 'val1','key2' => 'val2')
);

對(duì)于數(shù)組中的每個(gè)數(shù)組(即二"、三"和四")，我想將key3"=>val3"插入這些數(shù)組中.

and for each of the arrays in the array (that is, 'two, 'three', and 'four'), I want to insert 'key3' => 'val3' into those arrays.

我試過(guò)了:

foreach($array as $item) {
    if (gettype($item) == "array") {
        $item['key3'] = 'val3';
    }
}

但它不起作用，我不知道為什么.到處使用各種print_r，如果我在循環(huán)中將其打印出來(lái)，它似乎將'key3' => 'val3' 插入到$item 中，但原始數(shù)組似乎沒(méi)有變化.我也試過(guò)一個(gè)普通的 for 循環(huán)，但也沒(méi)有用.

But it doesn't work, and I'm not sure why. Using various print_r's all over the place, it seems to insert 'key3' => 'val3' into $item if I print it out in the loop, but the original array seems unchanged. I also tried a regular for loop but that didn't work either.

推薦答案

foreach 與 $item 的副本一起使用，因此您無(wú)法修改 foreach 中的原始數(shù)組.解決此問(wèn)題的一種方法是使用 & 運(yùn)算符.

foreach works with a copy of $item, so you cannot modify your original array inside the foreach. One way to work around this is to use the & operator.

foreach($array as &$item) {
    if (is_array($item)) {
        $item['key3'] = 'val3';
    }
}

另一種更優(yōu)雅的方法是使用 array_walk():

Another, more elegant way would be to use array_walk():

array_walk($array, function (&$v, $k) { 
    if (is_array($v)) {
        $v['key3'] = 'val3';
    }
});

此示例適用于 PHP 5.3，其中引入了閉包.

This example will work from PHP 5.3, where Closures were introduced.

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