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json_decode
Decodes a JSON string
Description
mixed json_decode(
string $json,
boolnull $associative = null,
int $depth = 512,
int $flags = 0
)
Parameters
-
json
-
The json string being decoded.
This function only works with UTF-8 encoded strings.
Note:
PHP implements a superset of JSON as specified in the original
» RFC 7159.
-
associative
-
When true, JSON objects will be returned as
associative arrays; when false, JSON objects will be returned as objects.
When null, JSON objects will be returned as associative arrays or
objects 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.
Return Values
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.
Errors/Exceptions
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.
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($json, true));
?>
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 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;
?>
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: No error
NULL
Last error: Maximum stack depth exceeded
Example #5 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));
?>
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.
See Also
- json_encode
- json_last_error
- json_last_error_msg
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