从第一个谷歌点击“PHP对象到assoc数组”，我们有:

function object_to_array($data)
{
    if (is_array($data) || is_object($data))
    {
        $result = [];
        foreach ($data as $key => $value)
        {
            $result[$key] = (is_array($value) || is_object($value)) ? object_to_array($value) : $value;
        }
        return $result;
    }
    return $data;
}

来源是codesnippets.joyent.com。

与json_decode和json_encode的解决方案相比，这个解决方案似乎更快。下面是一个随机的基准测试(使用简单的时间测量):

$obj = (object) [
    'name'    =>'Mike',
    'surname' =>'Jovanson',
    'age'     =>'45',
    'time'    =>1234567890,
    'country' =>'Germany',
];

##### 100 000 cycles ######
* json_decode(json_encode($var))   : 4.15 sec
* object_to_array($var)            : 0.93 sec

当你从数据库中以对象的形式获取数据时，你可能想这样做:

// Suppose 'result' is the end product from some query $query

$result = $mysqli->query($query);
$result = db_result_to_array($result);

function db_result_to_array($result)
{
    $res_array = array();

    for ($count=0; $row = $result->fetch_assoc(); $count++)
        $res_array[$count] = $row;

    return $res_array;
}

只是对它进行类型转换

$array = (array) $yourObject;

从数组:

如果将一个对象转换为数组，则结果是一个数组，其元素是该对象的属性。键是成员变量名，但有几个明显的例外:整数属性不可访问;私有变量的类名在变量名之前;受保护变量的变量名前面有一个'*'。这些前置值的两边都是空字节。

示例:简单对象

$object = new StdClass;
$object->foo = 1;
$object->bar = 2;

var_dump( (array) $object );

输出:

array(2) {
  'foo' => int(1)
  'bar' => int(2)
}

示例:复杂对象

class Foo
{
    private $foo;
    protected $bar;
    public $baz;

    public function __construct()
    {
        $this->foo = 1;
        $this->bar = 2;
        $this->baz = new StdClass;
    }
}

var_dump( (array) new Foo );

输出(为清晰起见，编辑了\0s):

array(3) {
  '\0Foo\0foo' => int(1)
  '\0*\0bar' => int(2)
  'baz' => class stdClass#2 (0) {}
}

输出var_export而不是var_dump:

array (
  '' . "\0" . 'Foo' . "\0" . 'foo' => 1,
  '' . "\0" . '*' . "\0" . 'bar' => 2,
  'baz' =>
  stdClass::__set_state(array(
  )),
)

以这种方式进行类型转换不会对对象图进行深度转换，您需要应用null字节(如手册引用中所解释的那样)来访问任何非公共属性。因此，当强制转换StdClass对象或只有公共属性的对象时，这种方法效果最好。快速和肮脏(你所要求的)是可以的。

也可以看看这篇深入的博客文章:

快速PHP对象到数组的转换

下面是将PHP对象转换为关联数组的递归PHP函数:

// ---------------------------------------------------------
// ----- object_to_array_recursive --- function (PHP) ------
// ---------------------------------------------------------
// --- arg1: -- $object  =  PHP Object         - required --
// --- arg2: -- $assoc   =  TRUE or FALSE      - optional --
// --- arg3: -- $empty   =  '' (Empty String)  - optional --
// ---------------------------------------------------------
// ----- Return: Array from Object --- (associative) -------
// ---------------------------------------------------------

function object_to_array_recursive($object, $assoc=TRUE, $empty='')
{
    $res_arr = array();

    if (!empty($object)) {

        $arrObj = is_object($object) ? get_object_vars($object) : $object;

        $i=0;
        foreach ($arrObj as $key => $val) {
            $akey = ($assoc !== FALSE) ? $key : $i;
            if (is_array($val) || is_object($val)) {
                $res_arr[$akey] = (empty($val)) ? $empty : object_to_array_recursive($val);
            }
            else {
                $res_arr[$akey] = (empty($val)) ? $empty : (string)$val;
            }
            $i++;
        }
    }
    return $res_arr;
}

// ---------------------------------------------------------
// ---------------------------------------------------------

使用的例子:

// ---- Return associative array from object, ... use:
$new_arr1 = object_to_array_recursive($my_object);
// -- or --
// $new_arr1 = object_to_array_recursive($my_object, TRUE);
// -- or --
// $new_arr1 = object_to_array_recursive($my_object, 1);


// ---- Return numeric array from object, ... use:
$new_arr2 = object_to_array_recursive($my_object, FALSE);

这里发布的所有其他答案都只使用公共属性。下面是一个使用反射和getter处理类javabean对象的解决方案:

function entity2array($entity, $recursionDepth = 2) {
    $result = array();
    $class = new ReflectionClass(get_class($entity));
    foreach ($class->getMethods(ReflectionMethod::IS_PUBLIC) as $method) {
        $methodName = $method->name;
        if (strpos($methodName, "get") === 0 && strlen($methodName) > 3) {
            $propertyName = lcfirst(substr($methodName, 3));
            $value = $method->invoke($entity);

            if (is_object($value)) {
                if ($recursionDepth > 0) {
                    $result[$propertyName] = $this->entity2array($value, $recursionDepth - 1);
                }
                else {
                    $result[$propertyName] = "***";  // Stop recursion
                }
            }
            else {
                $result[$propertyName] = $value;
            }
        }
    }
    return $result;
}

自定义函数将stdClass转换为数组:

function objectToArray($d) {
    if (is_object($d)) {
        // Gets the properties of the given object
        // with get_object_vars function
        $d = get_object_vars($d);
    }

    if (is_array($d)) {
        /*
        * Return array converted to object
        * Using __FUNCTION__ (Magic constant)
        * for recursive call
        */
        return array_map(__FUNCTION__, $d);
    } else {
        // Return array
        return $d;
    }
}

另一个将Array转换为stdClass的自定义函数:

function arrayToObject($d) {
    if (is_array($d)) {
        /*
        * Return array converted to object
        * Using __FUNCTION__ (Magic constant)
        * for recursive call
        */
        return (object) array_map(__FUNCTION__, $d);
    } else {
        // Return object
        return $d;
    }
}

使用的例子:

// Create new stdClass Object
$init = new stdClass;

// Add some test data
$init->foo = "Test data";
$init->bar = new stdClass;
$init->bar->baaz = "Testing";
$init->bar->fooz = new stdClass;
$init->bar->fooz->baz = "Testing again";
$init->foox = "Just test";

// Convert array to object and then object back to array
$array = objectToArray($init);
$object = arrayToObject($array);

// Print objects and array
print_r($init);
echo "\n";
print_r($array);
echo "\n";
print_r($object);