PHP: Strange Array Behaviour After Object Type Casting to Array

Question

When you do array type-casting of json_decoded value (with $assoc = false), PHP creates an array with string indices:

$a = (array)json_decode('{"7":"value1","8":"value2","9":"value3","13":"value4"}');

var_export($a);

//array (
//  '7' => 'value1',
//  '8' => 'value2',
//  '9' => 'value3',
//  '13' => 'value4',
//)

And for some reason these indices are not accessible:

var_dump(isset($a[7]), isset($a['7']));

//false
//false

When you try to create the same array by PHP itself, it is being created with numeric indices (string are automatically converted), and values are accessible using both strings and numbers:

$c = array('7' => 'value1', '8' => 'value2', '9' => 'value3','10' => 'value4');

var_export($c);

var_dump(isset($c[7]), isset($c['7']));

//array (
//  7 => 'value1',
//  8 => 'value2',
//  9 => 'value3',
//  13 => 'value4',
//)
//
//true
//true

Does anybody know what is going on here? Is it some bug of older PHP versions (the issue seems to be fixed on PHP version >= 7.2, but I can't find anything related in changelog)?

Here's the demo of what is going on: https://3v4l.org/da9CJ.

@LawrenceCherone please read the question carefully, it fails for older PHP versions (the second output tab on 3v4l.org) — Gino Pane
– Gino Pane, Commented Jan 22, 2018 at 10:59
Yeah I saw that, sorry. I guess you should be using the second param then and its fine. — Lawrence Cherone
– Lawrence Cherone, Commented Jan 22, 2018 at 11:01

deceze · Accepted Answer · 2018-01-22 11:02:55Z

3

This seems to be related to bug #61655 fixed in 7.2.0:

in a object property lookup by name always in string, but in array numeric string(like "22200" ) key will transform to numeric but not a string anymore. when conversion internal HashTable did't changed so after conversion, key lookup will fail.

Clarified: $a["2000"] is always interpreted as $a[2000], but (array) failed to cast object string keys to numbers. So the array contained string numeric indices, but the array syntax' automatic casting prevented those from being accessible.

answered Jan 22, 2018 at 11:02

deceze♦

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3 Comments

Gino Pane Over a year ago

Indeed! Thanks, I looked for something related to "json_decode", not for generic type-casting.

Death-is-the-real-truth Over a year ago

@GinoPane i will recomend you to always use true when you need type casting. Check once my answer as two different version are working perfectly fine.

Gino Pane Over a year ago

@AlivetoDie, thanks! Actually, I do use it (you can check my demo link and see the test-case with true passed). The reason for the question was, that I faced json_decode usage without second parameter and couldn't explain the magic with array indices.

Death-is-the-real-truth · Accepted Answer · 2018-01-22 13:52:53Z

0

add TRUE to json_decode()

<?php
$a = json_decode('{"7":"value1","8":"value2","9":"value3","13":"value4"}',TRUE);

var_export($a);

var_dump(isset($a[7]), isset($a['7']));

https://3v4l.org/YuF9B

edited Jan 22, 2018 at 13:52

Death-is-the-real-truth

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answered Jan 22, 2018 at 11:03

Abanoub Makram

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Comments

Andreas · Accepted Answer · 2018-07-19 10:09:35Z

0

add TRUE to json_decode() is possible, but it will couse to recode everything.

Becouse you have to change the access to the variables.

if your json look like this:

$return = '{"status":"ok","message":"","code":"200","data":{"1234":{"sid":1,"name":"foo"},"4321":{"sid":2,"name":"bar"}}}';

on:

$json_data = json_decode($return, true);
$data = $json_data['data'];

you can loop the $data and have to access the values as array: $data[0]['name'] ...

on:

$json_data = json_decode($return);
$data = (array) $json_data->data;

you can loop the $data and have to access the values as objects: $data[0]->name ...

answered Jul 19, 2018 at 10:09

Andreas

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