json_decode

Decodes a JSON string

&reftitle.description; `mixed` `json_decode` `string` `json` ``bool``null```associative`&null; `int` `depth` 512 `int` `flags` 0

Takes a JSON encoded string and converts it into a PHP value.

&reftitle.parameters;

`json`

- The `json` `string` being decoded.

  This function only works with UTF-8 encoded strings.

  &json.implementation.superset;

`associative`

- When &true;, JSON objects will be returned as associative &array;s; when &false;, JSON objects will be returned as &object;s. When &null;, JSON objects will be returned as associative &array;s or &object;s depending on whether `JSON_OBJECT_AS_ARRAY` is set in the `flags`.

`depth`

- Maximum nesting depth of the structure being decoded. The value must be greater than `0`, and less than or equal to `2147483647`.

`flags`

- Bitmask of `JSON_BIGINT_AS_STRING`, `JSON_INVALID_UTF8_IGNORE`, `JSON_INVALID_UTF8_SUBSTITUTE`, `JSON_OBJECT_AS_ARRAY`, `JSON_THROW_ON_ERROR`. The behaviour of these constants is described on the JSON constants page.

&reftitle.returnvalues;

Returns the value encoded in `json` as an appropriate PHP type. Unquoted values `true`, `false` and `null` are returned as &true;, &false; and &null; respectively. &null; is returned if the `json` cannot be decoded or if the encoded data is deeper than the nesting limit.

&reftitle.errors;

If `depth` is outside the allowed range, a `ValueError` is thrown as of PHP 8.0.0, while previously, an error of level `E_WARNING` was raised.

&reftitle.changelog;

&Version; | &Description;
7.3.0 | `JSON_THROW_ON_ERROR` `flags` was added.
7.2.0 | `associative` is nullable now.
7.2.0 | `JSON_INVALID_UTF8_IGNORE`, and `JSON_INVALID_UTF8_SUBSTITUTE` `flags` were added.
7.1.0 | An empty JSON key ("") can be encoded to the empty object property instead of using a key with value `_empty_`.

&reftitle.examples;

### `json_decode` examples

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

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

    ?>

&example.outputs;

    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)
    }

### Accessing invalid object properties

Accessing elements within an object that contain characters not permitted under PHP's naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.

    <?php

    $json = '{"foo-bar": 12345}';

    $obj = json_decode($json);
    print $obj->{'foo-bar'}; // 12345

    ?>

### common mistakes using `json_decode`

    <?php

    // the following strings are valid JavaScript but not valid JSON

    // the name and value must be enclosed in double quotes
    // single quotes are not valid
    $bad_json = "{ 'bar': 'baz' }";
    json_decode($bad_json); // null

    // the name must be enclosed in double quotes
    $bad_json = '{ bar: "baz" }';
    json_decode($bad_json); // null

    // trailing commas are not allowed
    $bad_json = '{ bar: "baz", }';
    json_decode($bad_json); // null

    ?>

### `depth` errors

    <?php
    // Encode some data with a maximum depth  of 4 (array -> array -> array -> string)
    $json = json_encode(
        array(
            1 => array(
                'English' => array(
                    'One',
                    'January'
                ),
                'French' => array(
                    'Une',
                    'Janvier'
                )
            )
        )
    );

    // Show the errors for different depths.
    var_dump(json_decode($json, true, 4));
    echo 'Last error: ', json_last_error_msg(), PHP_EOL, PHP_EOL;

    var_dump(json_decode($json, true, 3));
    echo 'Last error: ', json_last_error_msg(), PHP_EOL, PHP_EOL;
    ?>

&example.outputs;

    array(1) {
      [1]=>
      array(2) {
        ["English"]=>
        array(2) {
          [0]=>
          string(3) "One"
          [1]=>
          string(7) "January"
        }
        ["French"]=>
        array(2) {
          [0]=>
          string(3) "Une"
          [1]=>
          string(7) "Janvier"
        }
      }
    }
    Last error: No error

    NULL
    Last error: Maximum stack depth exceeded

### `json_decode` of large integers

    <?php
    $json = '{"number": 12345678901234567890}';

    var_dump(json_decode($json));
    var_dump(json_decode($json, false, 512, JSON_BIGINT_AS_STRING));

    ?>

&example.outputs;

    object(stdClass)#1 (1) {
      ["number"]=>
      float(1.2345678901235E+19)
    }
    object(stdClass)#1 (1) {
      ["number"]=>
      string(20) "12345678901234567890"
    }

&reftitle.notes;

The JSON spec is not JavaScript, but a subset of JavaScript.

In the event of a failure to decode, `json_last_error` can be used to determine the exact nature of the error.

&reftitle.seealso;

- `json_encode`
- `json_last_error`