As others have pointed out, you can use stdClass. However based on the question, it seems like what you really want is to be able to add properties to an object on the fly. You don't need to use stdClass for that, although you can. Really you can use any class. Just create an object instance of any class and start setting properties. I like to create my own class whose name is simply o with some basic extended functionality that I like to use in these cases and is nice for extending from other classes. Basically it is my own base object class. I also like to have a function simply named o(). Like so:

class o {
  // some custom shared magic, constructor, properties, or methods here
}

function o() {
  return new o();
}

If you don't like to have your own base object type, you can simply have o() return a new stdClass. One advantage is that o is easier to remember than stdClass and is shorter, regardless of if you use it as a class name, function name, or both. Even if you don't have any code inside your o class, it is still easier to memorize than the awkwardly capitalized and named stdClass (which may invoke the idea of a 'sexually transmitted disease class'). If you do customize the o class, you might find a use for the o() function instead of the constructor syntax. It is a normal function that returns a value, which is less limited than a constructor. For example, a function name can be passed as a string to a function that accepts a callable parameter. A function also supports chaining. So you can do something like: $result= o($internal_value)->some_operation_or_conversion_on_this_value();

这是基础“语言”构建其他语言层的一个很好的开始，顶层是用完整的内部dsl编写的。这类似于lisp开发风格，PHP对它的支持比大多数人想象的要好得多。我意识到这个问题有点离题，但这个问题涉及到我认为的充分利用PHP功能的基础。

EDIT/UPDATE: I no longer recommend any of this. It makes it hard for static analysis tools and IDEs and custom AST based tools to understand, validate, help you lookup or write your code. Generally magic is bad except in some cases if you are able to get your tools to understand the magic and if it you do it in a standard enough way that even standard community tools will understand it or if your tools are so advanced and full featured that you only use your own tools. Also, I think they are deprecating the ability to add properties to random objects in an upcoming version of PHP, I think it will only work with certain ones, but I don't recommend using that feature anyways.

我想指出的是，在PHP中，没有像空对象这样的东西:

$obj = new stdClass();
var_dump(empty($obj)); // bool(false)

当然$obj是空的。

另一方面，空数组在两种情况下都是空的

$arr = array();
var_dump(empty($arr));

引用changelog函数为空

没有属性的对象不再被认为是空的。

你也可以通过解析JSON得到一个空对象:

$blankObject= json_decode('{}');

你可以使用new stdClass()(这是推荐的):

$obj_a = new stdClass();
$obj_a->name = "John";
print_r($obj_a);

// outputs:
// stdClass Object ( [name] => John ) 

或者你可以将一个空数组转换为一个对象，该对象会生成stdClass内置类的一个新的空实例:

$obj_b = (object) [];
$obj_b->name = "John";
print_r($obj_b);

// outputs: 
// stdClass Object ( [name] => John )  

或者你可以将空值转换为一个对象，该对象会生成stdClass内置类的一个新的空实例:

$obj_c = (object) null;
$obj_c->name = "John";
print($obj_c);

// outputs:
// stdClass Object ( [name] => John ) 

这里有一个迭代的例子:

<?php
$colors = (object)[];
$colors->red = "#F00";
$colors->slateblue = "#6A5ACD";
$colors->orange = "#FFA500";

foreach ($colors as $key => $value) : ?>
    <p style="background-color:<?= $value ?>">
        <?= $key ?> -> <?= $value ?>
    </p>
<?php endforeach; ?>

stdClass是默认的PHP对象。stdClass没有属性、方法或父类。它不支持魔术方法，也不实现任何接口。

当您将标量或数组强制转换为Object时，您将获得stdClass的实例。只要需要泛型对象实例，就可以使用stdClass。

<?php
// ways of creating stdClass instances
$x = new stdClass;
$y = (object) null;        // same as above
$z = (object) 'a';         // creates property 'scalar' = 'a'
$a = (object) array('property1' => 1, 'property2' => 'b');
?>

stdClass不是基类!PHP类不会自动继承任何类。所有的类都是独立的，除非它们显式地扩展另一个类。PHP在这方面不同于许多面向对象的语言。

<?php
// CTest does not derive from stdClass
class CTest {
    public $property1;
}
$t = new CTest;
var_dump($t instanceof stdClass);            // false
var_dump(is_subclass_of($t, 'stdClass'));    // false
echo get_class($t) . "\n";                   // 'CTest'
echo get_parent_class($t) . "\n";            // false (no parent)
?>

你不能在你的代码中定义一个名为stdClass的类。该名称已被系统使用。你可以定义一个名为“Object”的类。

您可以定义一个扩展stdClass的类，但是您不会得到任何好处，因为stdClass什么也不做。

(在PHP 5.2.8上测试)