说明 ¶
$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
json
string 格式的字符串。这个函数仅能处理 UTF-8 编码的数据。
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 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. |
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 ¶
参见 ¶
- json_encode() - 对变量进行 JSON 编码
- json_last_error() - 返回最后发生的错误