为什么有json_decode（$ array，TRUE）？

Question

I send a dictionary as JSON to a server. The dictionary contains only 1 key, that is an array of items:

header('Content-type: application/json');

$request = json_decode(file_get_contents('php://input'));

$array = json_decode($request['array']);

The value for key 'array' is an array, can't be an object.

So, basically these two methods will return the same thing:

$array = json_decode($request['array']);

$array = json_decode($request['array'], TRUE);

Am I right?

The only use for this method is when you want to convert an object into an array:

$array = json_decode($request['object'], TRUE);

Why would you ever want to do that?

I mean, I do understand that there might be applications for this but on the other hand it took me a whole day to digest this way of thinking and it still feels like there's a huge mind gap.

This little convenience messes up with the concrete way of parsing data and is just confusing to a newbie like me.

Answer 1

There's a clear distinction between arrays and objects in Javascript/JSON. Arrays do not have explicit indices but are numerically indexed, while objects are unsorted and have named properties. By default json_decode honours this difference and decodes JSON arrays to PHP arrays and JSON objects to PHP objects (instances of stdClass ).

However, PHP's arrays also happen to support associative indices; so a JSON object could be decoded to either a PHP object or a PHP array. You can choose which you prefer with that second parameter to json_decode . There's no 100% clear 1:1 mapping between these two different languages here, so there's a preference instead.

Answer 2

Why the true is there, you can understand ,, See the following code below.

<?php
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';

var_dump(json_decode($json));
var_dump(json_decode($json, true));

?>

Output will be for the above code:

object(stdClass)#1 (5) {
    ["a"] => int(1)
    ["b"] => int(2)
    ["c"] => int(3)
    ["d"] => int(4)
    ["e"] => int(5)
}

array(5) {
    ["a"] => int(1)
    ["b"] => int(2)
    ["c"] => int(3)
    ["d"] => int(4)
    ["e"] => int(5)
}

Answer 3

简单如果您使用true，我将以数组格式显示，如果您不使用，将显示为