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);

我只是想指出这是一个折叠，所以可以使用array_reduce

array_reduce($my_array, 'array_merge', array());

编辑:注意，这可以组成平任意数量的水平。我们可以通过以下几种方式做到这一点:

// Reduces one level
$concat   = function($x) { return array_reduce($x, 'array_merge', array()); };

// We can compose $concat with itself $n times, then apply it to $x
// This can overflow the stack for large $n
$compose  = function($f, $g) {
    return function($x) use ($f, $g) { return $f($g($x)); };
};
$identity = function($x) { return $x; };
$flattenA = function($n) use ($compose, $identity, $concat) {
    return  function($x) use ($compose, $identity, $concat, $n) {
        return ($n === 0)? $x
                         : call_user_func(array_reduce(array_fill(0, $n, $concat),
                                                       $compose,
                                                       $identity),
                                          $x);
    };
};

// We can iteratively apply $concat to $x, $n times
$uncurriedFlip     = function($f) {
    return  function($a, $b) use ($f) {
        return $f($b, $a);
    };
};
$iterate  = function($f) use ($uncurriedFlip) {
    return  function($n) use ($uncurriedFlip, $f) {
    return  function($x) use ($uncurriedFlip, $f, $n) {
        return ($n === 0)? $x
                         : array_reduce(array_fill(0, $n, $f),
                                        $uncurriedFlip('call_user_func'),
                                        $x);
    }; };
};
$flattenB = $iterate($concat);

// Example usage:
$apply    = function($f, $x) {
    return $f($x);
};
$curriedFlip = function($f) {
    return  function($a) use ($f) {
    return  function($b) use ($f, $a) {
        return $f($b, $a);
    }; };
};

var_dump(
    array_map(
        call_user_func($curriedFlip($apply),
                       array(array(array('A', 'B', 'C'),
                                   array('D')),
                             array(array(),
                                   array('E')))),
        array($flattenA(2), $flattenB(2))));

当然，我们也可以使用循环，但这个问题要求的是一个组合子函数，类似于array_map或array_values。

仅平坦二维数组:

$arr = [1, 2, [3, 4]];
$arr = array_reduce($arr, function ($a, $b) {
     return array_merge($a, (array) $b);
}, []);

// Result: [1, 2, 3, 4]

试试下面这个简单的函数:

function _flatten_array($arr) {
  while ($arr) {
    list($key, $value) = each($arr); 
    is_array($value) ? $arr = $value : $out[$key] = $value;
    unset($arr[$key]);
  }
  return (array)$out;
}

所以从这里:

array (
  'und' => 
  array (
    'profiles' => 
    array (
      0 => 
      array (
        'commerce_customer_address' => 
        array (
          'und' => 
          array (
            0 => 
            array (
              'first_name' => 'First name',
              'last_name' => 'Last name',
              'thoroughfare' => 'Address 1',
              'premise' => 'Address 2',
              'locality' => 'Town/City',
              'administrative_area' => 'County',
              'postal_code' => 'Postcode',
            ),
          ),
        ),
      ),
    ),
  ),
)

你会得到:

array (
  'first_name' => 'First name',
  'last_name' => 'Last name',
  'thoroughfare' => 'Address 1',
  'premise' => 'Address 2',
  'locality' => 'Town/City',
  'administrative_area' => 'County',
  'postal_code' => 'Postcode',
)

您可以使用标准PHP库(SPL)来“隐藏”递归。

$a = array(1,2,array(3,4, array(5,6,7), 8), 9);
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($a));
foreach($it as $v) {
  echo $v, " ";
}

打印

1 2 3 4 5 6 7 8 9