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json_decode

(PHP 5 >= 5.2.0, PECL json >= 1.2.0)

json_decodeDecodes a JSON string

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.

Parameters

json

The json string being decoded.

This function only works with UTF-8 encoded strings.

Note:

PHP implements a superset of JSON - it will also encode and decode scalar types and NULL. The JSON standard only supports these values when they are nested inside an array or an object.

assoc

When TRUE, returned objects will be converted into associative arrays.

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)

Return Values

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.

Examples

Example #1 json_decode() examples

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

var_dump(json_decode($json));
var_dump(json_decode($jsontrue));

?>

The above example will output:

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)
}

Example #2 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

?>

Example #3 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

?>

Example #4 depth errors

<?php
// Encode the data.
$json json_encode(
    array(
        
=> 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(43, -1) as $depth) {
    
var_dump(json_decode($jsontrue$depth));
    echo 
'Last error: '$json_errors[json_last_error()], PHP_EOLPHP_EOL;
}
?>

The above example will output:

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

Example #5 json_decode() of large integers

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

var_dump(json_decode($json));
var_dump(json_decode($jsonfalse512JSON_BIGINT_AS_STRING));

?>

The above example will output:

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

Notes

Note:

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

Note:

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

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.

See Also

PHP Manual