Php/docs/function.json-decode
json_decode
(PHP 5 >= 5.2.0, PHP 7, PECL json >= 1.2.0)
json_decode — 对 JSON 格式的字符串进行解码
说明
json_decode
( string $json
[, bool $assoc = false
[, int $depth = 512
[, int $options = 0
]]] ) : mixed
接受一个 JSON 编码的字符串并且把它转换为 PHP 变量
参数
json待解码的
jsonstring 格式的字符串。这个函数仅能处理 UTF-8 编码的数据。
Note:
PHP 实现了 JSON 的一个超集，参考 » RFC 7159.
assoc当该参数为
true时，将返回 array 而非 object 。depth指定递归深度。
options由
JSON_BIGINT_AS_STRING,JSON_INVALID_UTF8_IGNORE,JSON_INVALID_UTF8_SUBSTITUTE,JSON_OBJECT_AS_ARRAY,JSON_THROW_ON_ERROR组成的掩码。 这些常量的行为在JSON constants页面有进一步描述。
返回值
通过恰当的 PHP 类型返回在 json
中编码的数据。值true, false 和 null
会相应地返回 true, false 和 null。
如果 json 无法被解码，
或者编码数据深度超过了递归限制的话，将会返回null 。
更新日志
| 版本 | 说明 |
|---|---|
| 7.3.0 | JSON_THROW_ON_ERROR
|
| 7.2.0 | JSON_INVALID_UTF8_IGNORE, and
|
| 7.1.0 | An empty JSON key ("") can be encoded to the empty object property
instead of using a key with value |
| 7.0.0 | Rejected RFC 7159 incompatible number formats - top level
(07, 0xff, .1, -.1) and all levels ([1.], [1.e1]) |
| 7.0.0 | An empty PHP string or value that after casting to string is an empty
string ( |
| 5.6.0 | Invalid non-lowercased variants of the true,
|
| 5.4.0 | JSON_BIGINT_AS_STRING, and
|
| 5.4.0 | The options parameter was added.
|
| 5.3.0 | Added the optional depth. The default
recursion depth was increased from 128 to 512 |
| 5.2.3 | The nesting limit was increased from 20 to 128 |
| 5.2.1 | Added support for JSON decoding of basic types. |
范例
Example #1 json_decode() 的例子
<?php$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';var_dump(json_decode($json));var_dump(json_decode($json, true));?>
以上例程会输出：
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)
}
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.$json = json_encode( array( 1 => array( 'English' => array( 'One', 'January' ), 'French' => array( 'Une', 'Janvier' ) ) ));// Define the errors.$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: ', $json_errors[json_last_error()], PHP_EOL, PHP_EOL;}?>
以上例程会输出：
array(1) {
[1]=>
array(2) {
["English"]=>
array(2) {
[0]=>
string(3) "One"
[1]=>
string(7) "January"
}
["French"]=>
array(2) {
[0]=>
string(3) "Une"
[1]=>
string(7) "Janvier"
}
}
}
Last error: JSON_ERROR_NONE
NULL
Last error: JSON_ERROR_DEPTH
Example #5 json_decode() of large integers
<?php$json = '{"number": 12345678901234567890}';var_dump(json_decode($json));var_dump(json_decode($json, false, 512, JSON_BIGINT_AS_STRING));?>
以上例程会输出：
object(stdClass)#1 (1) {
["number"]=>
float(1.2345678901235E+19)
}
object(stdClass)#1 (1) {
["number"]=>
string(20) "12345678901234567890"
}
注释
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.
