Description:
------------
php treat numeric string key as interge,

bug sometimes there is some exception.

for example:
  while change a std object to array, numeric string key doesn't cast to number 

Test script:
---------------
<?php
$data = array(
    123 => 'laruence',
    "03"=> 'baidu',
);

$value = json_encode($data);
$obj   = json_decode($value);
$arr   = (array)$obj;
var_dump($arr);
?>

Expected result:
----------------
array(2) {
  [123]=>
  string(8) "laruence"
  ["03"]=>
  string(5) "baidu"
}


Actual result:
--------------
array(2) {
  ["123"]=>
  string(8) "laruence"
  ["03"]=>
  string(5) "baidu"
}