json_decode

Decodes a JSON string

&reftitle.description; `mixed` `json_decode` `string` `json` `bool` `assoc` false `int` `depth` 512 `int` `options` 0

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

&reftitle.parameters;

`json`

- The `json` `string` being decoded.

  This function only works with UTF-8 encoded strings.

  &json.implementation.superset;

`assoc`

- When &true;, returned `object`s will be converted into associative `array`s.

`depth`

- User specified recursion depth.

`options`

- Bitmask of JSON decode options. Currently only `JSON_BIGINT_AS_STRING` is supported (default is to cast large integers as floats)

&reftitle.returnvalues;

Returns the value encoded in `json` in appropriate PHP type. Values `true`, `false` and `null` (case-insensitive) 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 recursion limit.

&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 the data.
    $json = json_encode(
        array(
            1 => array(
                'English' => array(
                    'One',
                    'January'
                ),
                'French' => array(
                    'Une',
                    'Janvier'
                )
            )
        )
    );

    // Define the errors.
    $constants = get_defined_constants(true);
    $json_errors = array();
    foreach ($constants["json"] as $name => $value) {
        if (!strncmp($name, "JSON_ERROR_", 11)) {
            $json_errors[$value] = $name;
        }
    }

    // Show the errors for different depths.
    foreach (range(4, 3, -1) as $depth) {
        var_dump(json_decode($json, true, $depth));
        echo 'Last error: ', $json_errors[json_last_error()], 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: JSON_ERROR_NONE

    NULL
    Last error: JSON_ERROR_DEPTH

### `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.changelog;

&Version; | &Description;
5.4.0 | The `options` parameter was added.
5.3.0 | Added the optional `depth`. The default recursion depth was increased from 128 to 512
5.2.3 | The nesting limit was increased from 20 to 128
5.2.1 | Added support for JSON decoding of basic types.

&reftitle.seealso;

- `json_encode`
- `json_last_error`