PHP在关联数组中增加了一个新的键值对

Question

你好，我需要帮助。我有一个像这样的数组

$my_array = array(
    array(
        'key_1' => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
        'key_2'     => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
        'key_3'     => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
    ),
    array(
        'key_1' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
        'key_2' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
        'key_3' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
    ),
    array(
        'key_1' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
        'key_2' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
        'key_3' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
    ),
);

我想做的是在每个内部数组项上附加一个key_4 => value_4，所以为了做到这一点，我使用了一个foreach循环，如下所示:

foreach ($my_array as $item) {
            $item['key_4'] = file_get_contents($some_file);
            // echo '<pre>'. print_r($item) . '</pre>'; // the new keys seems to appended properly here
}
echo '<pre>'. print_r($my_array) . '</pre>'; // the new keys are not in my array (!!!)

所以我要做的是:

$my_array = array(
        array(
            'key_1' => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
            'key_2'     => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
            'key_3'     => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
            'key_4'     => 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
        ),
        array(
            'key_1' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
            'key_2' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
            'key_3' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
            'key_4' => 'Integer lorem quam, adipiscing condimentum tristique vel, eleifend sed turpis.',
        ),
        array(
            'key_1' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
            'key_2' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
            'key_3' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
            'key_4' => 'Pellentesque cursus arcu id magna euismod in elementum purus molestie.',
        ),
    );

但是，如果我转储我的数组(看到print_r退出循环)，我没有得到新的键=>对项目。你知道我做错了什么吗?

Answer 1

默认情况下，foreach创建一个数组副本。

在原来的基础上，通过引用进行迭代:

foreach ($my_array as &$item){ //note & char

或者使用for循环

for($i = 0; $i < count($my_array); $i++){
    $my_array[$i]['key_4'] = file_get_contents($some_file);

或者您可以使用array_map:

$my_array = array_map(function($item){
    $item['key_4'] = file_get_contents($some_file);
    return $item;
    }, $my_array);

这将使用修改后的副本覆盖原始数组，因此可能比其他两个选项

Answer 2

您需要使用主数组的当前key来存储新值。试试这个-

foreach ($my_array as $key => $item) {
    $my_array[$key]['key_4'] = //new value;
}