如果你想保留中间键:

function flattenArray(array &$result, $value, string $key = "")
{
    if (!is_array($value)) {
        $result[$key] = $value;
        return $result;
    }
    foreach ($value as $subKey => $subArray) {
        $newKey = $key !== "" ? $key . "_" . $subKey : $subKey;
        flattenArray($result, $subArray, $newKey);
    }
    return $result;
}

$nestedArray = [
    "name" => "John",
    "pets" => [
        ["id" => 1, "name" => "snooop"],
        ["id" => 2, "name" => "medor"],
    ],
    "job" => ["title" => "developper"],
];

$intermediateResult = [];
$flattened = flattenArray($intermediateResult, $nestedArray);
var_dump($flattened);

这将输出:

array(6) {
["name"]=>
  string(4) "John"
        ["pets_0_id"]=>
  int(1)
  ["pets_0_name"]=>
  string(6) "snooop"
        ["pets_1_id"]=>
  int(2)
  ["pets_1_name"]=>
  string(5) "medor"
        ["job_title"]=>
  string(10) "developper"
}

看到https://ideone.com/KXLtzZ stdout

因为这里的代码看起来很可怕。下面是一个将多维数组转换为html格式兼容语法的函数，但它更容易阅读。

/**
 * Flattens a multi demensional array into a one dimensional
 * to be compatible with hidden html fields.
 *
 * @param array $array
 *  Array in the form:
 *  array(
 *    'a' => array(
 *      'b' => '1'
 *    )
 *  )
 *
 * @return array
 *  Array in the form:
 *  array(
 *    'a[b]' => 1,
 *  )
 */
function flatten_array($array) {
  // Continue until $array is a one-dimensional array.
  $continue = TRUE;
  while ($continue) {
    $continue = FALSE;

    // Walk through top and second level of $array and move 
    // all values in the second level up one level.
    foreach ($array as $key => $value) {
      if (is_array($value)) {
        // Second level found, therefore continue.
        $continue = TRUE;

        // Move each value a level up.
        foreach ($value as $child_key => $child_value) {
          $array[$key . '[' . $child_key . ']'] = $child_value;
        }

        // Remove second level array from top level.
        unset($array[$key]);
      }
    }
  }

  return $array;
}

我相信这是最干净的解决方案，不使用任何突变或不熟悉的类。

<?php

function flatten($array)
{
    return array_reduce($array, function($acc, $item){
        return array_merge($acc, is_array($item) ? flatten($item) : [$item]);
    }, []);
}


// usage
$array = [1, 2, [3, 4], [5, [6, 7]], 8, 9, 10];
print_r(flatten($array));

任何想要解决这个问题的人;这里有一个选择:

获取具有不同键值配置的数组的数组:

$test_array = array(
    array('test' => 0, 0, 0, 0),
    array(0, 0, 'merp' => array('herp' => 'derp'), 0),
    array(0, 0, 0, 0),
    array(0, 0, 0, 0)
);
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($test_array));
var_dump( iterator_to_array($it, false) ) ; 

这将只从每个数组中获取值，并返回单个平面数组。

result值的输出:

0 0 0 0 0 0 derp 0 0 0 0 0 0 0 0 0

诀窍是通过引用传递源数组和目标数组。

function flatten_array(&$arr, &$dst) {
    if(!isset($dst) || !is_array($dst)) {
        $dst = array();
    }
    if(!is_array($arr)) {
        $dst[] = $arr;
    } else {
        foreach($arr as &$subject) {
            flatten_array($subject, $dst);
        }
    }
}

$recursive = array('1', array('2','3',array('4',array('5','6')),'7',array(array(array('8'),'9'),'10')));
echo "Recursive: \r\n";
print_r($recursive);
$flat = null;
flatten_array($recursive, $flat);

echo "Flat: \r\n";
print_r($flat);

// If you change line 3 to $dst[] = &$arr; , you won't waste memory,
// since all you're doing is copying references, and imploding the array 
// into a string will be both memory efficient and fast:)

echo "String:\r\n";
echo implode(',',$flat);

这个解是非递归的。注意，元素的顺序会有些混合。

function flatten($array) {
    $return = array();
    while(count($array)) {
        $value = array_shift($array);
        if(is_array($value))
            foreach($value as $sub)
                $array[] = $sub;
        else
            $return[] = $value;
    }
    return $return;
}