Description:
------------
When typecasting an object (stdClass in the example below) to an array and the object contains numeric members the result is a valid array as one might expect.

var_dumping the array shows all the keys and corresponding values just the way you might expect. However when an attempt is made to access one of the numeric array keys a notice Undefined <offset|index> is thrown and the key is inaccessible.

Several workarounds are possible, like json_encoding/decoding and doing an array_combine(array_keys(array), array_values(array)) fixes the problem as well.

Interesting is that the array_key_exists shows that the key does not exist while var_dumping the array_keys shows the key in question.
Also using array_search() on the value of the key returns the key in question.

This has been tested on:
PHP 5.2.0-8+etch16 (cli) (built: Nov 24 2009 11:14:47)
PHP 5.3.2

Both had the same issue.

Test script:
---------------
<?php
error_reporting(E_ALL);
$test_object = new stdClass();
$test_object->{1234} = "test";
var_dump($test_object); // object(stdClass)#1 (1) { ["1234"]=>  string(4) "test" } 
$test_array = (array) $test_object;
var_dump($test_array); // array(1) { ["1234"]=>  string(4) "test" }
$value = $test_array[1234]; // Results in "Notice: Undefined offset: 1234"
$value = $test_array["1234"]; // Results in "Undefined index: 1234"
var_dump(array_key_exists("1234", $test_array)); // bool(false)
var_dump(in_array("1234", array_keys($test_array))); // bool(true)
var_dump(array_search("test", $test_array)); // string(4) "1234"
$new_test_array = array_combine(array_keys($test_array), array_values($test_array));
var_dump(array_key_exists(1234, $new_test_array)); // bool(true)
$new_value = $new_test_array[1234]; // No notices thrown
var_dump($new_value); // string(4) "test"
?>

Expected result:
----------------
Expected would be the full accessibility of all array keys even after type casting between object and array.

Actual result:
--------------
The actual result is an array, that looks right, but has inaccessible keys.