Question

I would like to convert a list of values such as:

$foo = ['a', 'b', 'c'];

into a list of traversing array keys such as:

$bar['a']['b']['c'] = 123;

How I can create an associative array which keys are based on a set values stored in another array?

Answer 1

You can make it with reference. Try this code, live demo

<?php
$foo = ['a', 'b', 'c']; 
$array = [];
$current = &$array;
foreach($foo as $key) {
  @$current = &$current[$key];
}
$current = 123;
print_r($array);

Answer 2

我会这样做：

$foo = ['a', 'b', 'c']; 
$val = '123';
foreach (array_reverse($foo) as $k => $v) {
    $bar = [$v => $k ? $bar : $val];
}

我们反过来迭代数组并首先分配最里面的值，然后从里到外构建数组。

Answer 3

这是另一个选项：创建一个临时可解析字符串（通过提取第一个值，然后将其余值附加为方括号包裹的字符串），调用parse_str()，并将输出变量设置为$bar

代码：（Demo）

$foo = ['a', 'b', 'c'];
$val=123;

parse_str(array_shift($foo).'['.implode('][',$foo)."]=$val",$bar);
// built string: `a[b][c]=123`
var_export($bar);

输出：

array (
  'a' => 
  array (
    'b' => 
    array (
      'c' => '123',
    ),
  ),
)

如果第一种方法感觉过于苛刻，以下递归方法是一种稳定的方法：

代码：（Demo）

function nest_assoc($keys,$value){
    return [array_shift($keys) => (empty($keys) ? $value : nest_assoc($keys,$value))];
    //      ^^^^^^^^^^^^^^^^^^--------------------------------------------------------extract leading key value, modify $keys
    //  check if any keys left-----^^^^^^^^^^^^
    //  no more keys, use the value---------------^^^^^^
    //  recurse to write the subarray contents-------------^^^^^^^^^^^^^^^^^^^^^^^^^
}

$foo=['a','b','c'];
$val=123;

var_export(nest_assoc($foo,$val));
// same output

How to set a list of values as keys in a multidimensional associative array?

3 个答案: