Reproduced with the Win32 CVS build:

PHP 5.2.4RC1-dev (cli) (built: Aug 12 2007 00:04:25)
Copyright (c) 1997-2007 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2007 Zend Technologies

Workaround : use array_udiff with a supplied callback function or use only arrays.

See also bug #42303

Here's what I get for the encode:

{"first":[{"second":2},"two","three"]}

So actually you have another object inside the first, here's var_dump($obj);

object(stdClass)#1 (1) {
  ["first"]=>
  array(3) {
    [0]=>
    object(stdClass)#2 (1) {
      ["second"]=>
      int(2)
    }
    [1]=>
    string(3) "two"
    [2]=>
    string(5) "three"
  }
}

And using json_decode($json, true):

array(1) {
  ["first"]=>
  array(3) {
    [0]=>
    array(1) {
      ["second"]=>
      int(2)
    }
    [1]=>
    string(3) "two"
    [2]=>
    string(5) "three"
  }
}

So what's the bug?

The situation I'm using it in is where the browser sends an array of objects to PHP.  The PHP scripts uses PEAR::DB_DataObject to generate an array of objects inside a database table, I then use array_diff/array_udiff to calculate what is new, what has changed, and what should be deleted.  The array_diff for items that have not changed fails in 5.2 because PHP fails be able to compare some of the stdClass objects.

 $new_products = array_filter($products, array('Order','is_new_product'));
 debug('new_order_products: '.count($new_products).' found');
 $old_products = array_diff($new_products, $products);
 debug('old_order_products: '.count($old_products).' calculated');
 $updated_products = array_udiff($old_products, $current_products, array('Order', 'product_compare'));
 debug('updated_order_products: '.count($updated_products).' found');
 $deleted_products = array_udiff($current_products, $products, array('Order', 'product_compare_by_id'));
 debug('deleted_order_products: '.count($deleted_products).' found');


PEAR::DB_DataObject returns table rows as objects, the PHP JSON module defaults to objects, but can include arrays of objects as shown previously.

As a workaround I rebuilt PHP 5.1.6 from Ubuntu 6.10 on 7.04.  If someone can provide a array_udiff function that can compare objects like before that would be great :-)

If the current circumstances are not clear, I will repeat:  PHP 5.1.6 generates the expected result output as shown, PHP 5.2 does not.

So this has nothing to do with JSON? Please reclassify if that is true and fix the summary to contain what the bug is really about..

Well its either json_decode not making stdClass objects friendly for comparison or array_diff() that broke.  Lets try the latter then.

Okay, so you think array_diff() is broken. As our bug system sucks, can't edit original comment, etc. so please, open new short report about the array_diff issue. (this one is a bit confusing with the json stuff and all) And make sure the new report does not have any references to JSON. :D

This is really json problem. Although I have PHP 5.3.3 I have the same issue.

$params = json_decode($options);

This produce error

Object of class stdClass could not be converted to string

i solved i like this

$params = json_decode(trim(str_replace("\r\n", '\\n', $options)));