json_decode
(PHP 5 >= 5.2.0, PHP 7, PHP 8, PECL json >= 1.2.0)
json_decode — 對 JSON 格式的字串進行解碼
說明
接受一個 JSON 編碼的字串並且把它轉換為 PHP 變數
參數
-
json -
待解碼的
jsonstring 格式的字串。這個函式僅能處理 UTF-8 編碼的數據。
注意:
PHP 實現了 JSON 的一個超集，參考 » RFC 7159.
-
assoc -
當該參數為
true時，將返回 array 而非 object 。 -
depth -
指定遞迴深度。
-
options -
由
JSON_BIGINT_AS_STRING,JSON_INVALID_UTF8_IGNORE,JSON_INVALID_UTF8_SUBSTITUTE,JSON_OBJECT_AS_ARRAY,JSON_THROW_ON_ERROR組成的掩碼。 這些常量的行為在JSON constants頁面有進一步描述。
返回值
通過恰當的 PHP 型別返回在 json
中編碼的數據。值true, false 和 null
會相應地返回 true, false 和 null。
如果 json 無法被解碼，
或者編碼數據深度超過了遞迴限制的話，將會返回null 。
更新日誌
| 版本 | 說明 |
|---|---|
| 7.3.0 |
JSON_THROW_ON_ERROR
options was added.
|
| 7.2.0 |
JSON_INVALID_UTF8_IGNORE, and
JSON_INVALID_UTF8_SUBSTITUTE
options 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_.
|
| 7.0.0 | Rejected RFC 7159 incompatible number formats - top level (07, 0xff, .1, -.1) and all levels ([1.], [1.e1]) |
| 7.0.0 |
An empty PHP string or value that after casting to string is an empty
string (NULL, FALSE) results
in JSON syntax error.
|
| 5.6.0 |
Invalid non-lowercased variants of the true,
false and null literals are no
longer accepted as valid input, and will generate warnings.
|
| 5.4.0 |
JSON_BIGINT_AS_STRING, and
JSON_OBJECT_AS_ARRAY
options were added.
|
| 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. |
範例
示例 #1 json_decode() 的例子
<?php
$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
var_dump(json_decode($json));
var_dump(json_decode($json, true));
?>
以上例程會輸出：
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)
}
示例 #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
?>
示例 #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
?>
示例 #4 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;
}
?>
以上例程會輸出：
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
示例 #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));
?>
以上例程會輸出：
object(stdClass)#1 (1) {
["number"]=>
float(1.2345678901235E+19)
}
object(stdClass)#1 (1) {
["number"]=>
string(20) "12345678901234567890"
}
註釋
注意:
The JSON spec is not JavaScript, but a subset of JavaScript.
注意:
In the event of a failure to decode, json_last_error() can be used to determine the exact nature of the error.