What is stdClass in PHP?

请定义stdClass是什么。

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stdClass is PHP's generic empty class, kind of like Object in Java or object in Python ( Edit: but not actually used as universal base class; thanks @Ciaran for pointing this out).

It is useful for anonymous objects, dynamic properties, etc.

An easy way to consider the StdClass is as an alternative to associative array. See this example below that shows how json_decode() allows to get an StdClass instance or an associative array. Also but not shown in this example, SoapClient::__soapCall returns an StdClass instance.

<?php
//Example with StdClass
$json = '{ "foo": "bar", "number": 42 }';
$stdInstance = json_decode($json);
echo $stdInstance->foo . PHP_EOL; //"bar"
echo $stdInstance->number . PHP_EOL; //42
//Example with associative array
$array = json_decode($json, true);
echo $array['foo'] . PHP_EOL; //"bar"
echo $array['number'] . PHP_EOL; //42

See Dynamic Properties in PHP and StdClass for more examples.

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stdClass is just a generic 'empty' class that's used when casting other types to objects. Despite what the other two answers say, stdClass is not the base class for objects in PHP. This can be demonstrated fairly easily:

class Foo{}
$foo = new Foo();
echo ($foo instanceof stdClass)?'Y':'N';
// outputs 'N'

I don't believe there's a concept of a base object in PHP

---

stdClass is a another great PHP feature. You can create a anonymous PHP class. Lets check an example.

$page=new stdClass();
$page->name='Home';
$page->status=1;

now think you have a another class that will initialize with a page object and execute base on it.

<?php
class PageShow {

    public $currentpage;

    public function __construct($pageobj)
    {
        $this->currentpage = $pageobj;
    }

    public function show()
    {
        echo $this->currentpage->name;
        $state = ($this->currentpage->status == 1) ? 'Active' : 'Inactive';
        echo 'This is ' . $state . ' page';
    }
}

Now you have to create a new PageShow object with a Page Object.

Here no need to write a new Class Template for this you can simply use stdClass to create a Class on the fly.

    $pageview=new PageShow($page);
    $pageview->show();

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