Can't access array element by numeric associative key when converted from object

Question

When you convert object with numeric fields (see $obj) to array you can't access it elements

$obj = new stdClass();
$obj->{"325890"} = "test";

$arr = (Array) $obj;

$key = array_keys($arr)[0];

var_dump($arr); // array (size=1) '325890' => string 'test' (length=4)
var_dump($key); // string '325890' (length=6)

var_dump($arr["325890"]); // null
var_dump($arr[325890]); // null
var_dump($arr[$key]); // null

$arr = unserialize(serialize($arr)); // this fixes that

var_dump($arr["325890"]); // string 'test' (length=4);

Also something strange happens when you assign data to same element:

$arr = (Array) $obj;
$arr[325890] = "test"; // or $arr["325890"] = "test";

var_dump($arr);

array (size=2)
'325890' => string 'test' (length=4)
325890 => string 'test' (length=4)

Is this a bug or documented behaviour? I am using PHP 7.1.2

I discovered thin bug when trying to access JSON elements with numeric keys.

$items = Array(
   "100" => "item",
   "200" => "item",
   "300" => "item",
   "400" => "item",
);

$json = json_encode($items);

$items = (Array) json_decode($json);

var_dump($items[100]); // null

@JonStirling I don't get what you are trying to say. `$arr["123"] = ..` is same as `$arr[123] = ..` — Peter, Mar 23 '17 at 10:51
While normally the case, I'm wondering if the obj -> array cast doesn't get treated that way. The rest is admittedly a bit odd... — Jonnix, Mar 23 '17 at 10:52
And also http://stackoverflow.com/questions/11515536/php-array-with-numeric-keys-as-string-cant-be-used But yeah, numeric object keys in PHP are a nightmare. — roberto06, Mar 23 '17 at 10:56
however, this will also fix `$arr = json_decode(json_encode($obj), true);` instead of casting your object, https://3v4l.org/jqRNp — hassan, Mar 23 '17 at 10:59

score 2 · Accepted Answer · answered Mar 23 '17 at 11:01

it is mentioned in the doc that "integer properties are unaccessible" http://php.net/manual/en/language.types.array.php

From the doc

If an object is converted to an array, the result is an array whose elements are the object's properties. The keys are the member variable names, with a few notable exceptions: integer properties are unaccessible; private variables have the class name prepended to the variable name; protected variables have a '*' prepended to the variable name. These prepended values have null bytes on either side. This can result in some unexpected behaviour:

Can't access array element by numeric associative key when converted from object

1 Answers1