json_encode

(PHP 5 >= 5.2.0, PHP 7, PECL json >= 1.2.0)

json_encode — 对变量进行 JSON 编码

说明

json_encode ( mixed $value [, int $options = 0 [, int $depth = 512 ]] ) : string|false

返回字符串，包含了 value 值 JSON 形式的表示。

编码受传入的 options 参数影响，此外浮点值的编码依赖于 serialize_precision。

参数

value

待编码的 value ，除了资源(resource) 类型之外，可以为任何数据类型。

所有字符串数据的编码必须是 UTF-8。

Note:

PHP 实现了 JSON 的一个超集，参考 » RFC 7159.

options

由以下常量组成的二进制掩码： JSON_FORCE_OBJECT, JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_INVALID_UTF8_IGNORE, JSON_INVALID_UTF8_SUBSTITUTE, JSON_NUMERIC_CHECK, JSON_PARTIAL_OUTPUT_ON_ERROR, JSON_PRESERVE_ZERO_FRACTION, JSON_PRETTY_PRINT, JSON_UNESCAPED_LINE_TERMINATORS, JSON_UNESCAPED_SLASHES, JSON_UNESCAPED_UNICODE, JSON_THROW_ON_ERROR。关于 JSON 常量详情参考 JSON 常量页面。

depth

设置最大深度。必须大于0。

返回值

成功则返回 JSON 编码的 string 或者在失败时返回 false 。

更新日志

版本	说明
7.3.0	`options` 参数新增 `JSON_THROW_ON_ERROR` 常量。
7.2.0	`options` 参数新增 `JSON_INVALID_UTF8_IGNORE` 和 `JSON_INVALID_UTF8_SUBSTITUTE` 常量。
7.1.0	`options` 参数新增 `JSON_UNESCAPED_LINE_TERMINATORS` 常量。
7.1.0	对 Double 的值进行编码时，使用 serialize_precision 代替 precision。

范例

Example #1 json_encode() 例子

<?php$arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);echo json_encode($arr);?>

以上例程会输出：

{"a":1,"b":2,"c":3,"d":4,"e":5}

Example #2 json_encode() 函数中 options 参数的用法

<?php$a = array('<foo>',"'bar'",'"baz"','&blong&', "\xc3\xa9");echo "Normal: ", json_encode($a), "\n";echo "Tags: ", json_encode($a, JSON_HEX_TAG), "\n";echo "Apos: ", json_encode($a, JSON_HEX_APOS), "\n";echo "Quot: ", json_encode($a, JSON_HEX_QUOT), "\n";echo "Amp: ", json_encode($a, JSON_HEX_AMP), "\n";echo "Unicode: ", json_encode($a, JSON_UNESCAPED_UNICODE), "\n";echo "All: ", json_encode($a, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE), "\n\n";$b = array();echo "Empty array output as array: ", json_encode($b), "\n";echo "Empty array output as object: ", json_encode($b, JSON_FORCE_OBJECT), "\n\n";$c = array(array(1,2,3));echo "Non-associative array output as array: ", json_encode($c), "\n";echo "Non-associative array output as object: ", json_encode($c, JSON_FORCE_OBJECT), "\n\n";$d = array('foo' => 'bar', 'baz' => 'long');echo "Associative array always output as object: ", json_encode($d), "\n";echo "Associative array always output as object: ", json_encode($d, JSON_FORCE_OBJECT), "\n\n";?>

以上例程会输出：

Normal: ["<foo>","'bar'","\"baz\"","&blong&","\u00e9"]
Tags: ["\u003Cfoo\u003E","'bar'","\"baz\"","&blong&","\u00e9"]
Apos: ["<foo>","\u0027bar\u0027","\"baz\"","&blong&","\u00e9"]
Quot: ["<foo>","'bar'","\u0022baz\u0022","&blong&","\u00e9"]
Amp: ["<foo>","'bar'","\"baz\"","\u0026blong\u0026","\u00e9"]
Unicode: ["<foo>","'bar'","\"baz\"","&blong&","é"]
All: ["\u003Cfoo\u003E","\u0027bar\u0027","\u0022baz\u0022","\u0026blong\u0026","é"]

Empty array output as array: []
Empty array output as object: {}

Non-associative array output as array: [[../1,2,3]]
Non-associative array output as object: {"0":{"0":1,"1":2,"2":3}}

Associative array always output as object: {"foo":"bar","baz":"long"}
Associative array always output as object: {"foo":"bar","baz":"long"}

Example #3 选项 JSON_NUMERIC_CHECK 例子

<?phpecho "Strings representing numbers automatically turned into numbers".PHP_EOL;$numbers = array('+123123', '-123123', '1.2e3', '0.00001');var_dump( $numbers, json_encode($numbers, JSON_NUMERIC_CHECK));echo "Strings containing improperly formatted numbers".PHP_EOL;$strings = array('+a33123456789', 'a123');var_dump( $strings, json_encode($strings, JSON_NUMERIC_CHECK));?>

以上例程的输出类似于：

Strings representing numbers automatically turned into numbers
array(4) {
  [0]=>
  string(7) "+123123"
  [1]=>
  string(7) "-123123"
  [2]=>
  string(5) "1.2e3"
  [3]=>
  string(7) "0.00001"
}
string(28) "[123123,-123123,1200,1.0e-5]"
Strings containing improperly formatted numbers
array(2) {
  [0]=>
  string(13) "+a33123456789"
  [1]=>
  string(4) "a123"
}
string(24) "["+a33123456789","a123"]"

Example #4 连续与非连续数组示例

<?phpecho "连续数组".PHP_EOL;$sequential = array("foo", "bar", "baz", "blong");var_dump( $sequential, json_encode($sequential));echo PHP_EOL."非连续数组".PHP_EOL;$nonsequential = array(1=>"foo", 2=>"bar", 3=>"baz", 4=>"blong");var_dump( $nonsequential, json_encode($nonsequential));echo PHP_EOL."删除一个连续数组值的方式产生的非连续数组".PHP_EOL;unset($sequential[1]);var_dump( $sequential, json_encode($sequential));?>

以上例程会输出：

连续数组
array(4) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
  [2]=>
  string(3) "baz"
  [3]=>
  string(5) "blong"
}
string(27) "["foo","bar","baz","blong"]"

非连续数组
array(4) {
  [1]=>
  string(3) "foo"
  [2]=>
  string(3) "bar"
  [3]=>
  string(3) "baz"
  [4]=>
  string(5) "blong"
}
string(43) "{"1":"foo","2":"bar","3":"baz","4":"blong"}"

删除一个连续数组值的方式产生的非连续数组
array(3) {
  [0]=>
  string(3) "foo"
  [2]=>
  string(3) "baz"
  [3]=>
  string(5) "blong"
}
string(33) "{"0":"foo","2":"baz","3":"blong"}"

Example #5 选项 JSON_PRESERVE_ZERO_FRACTION 的例子

<?phpvar_dump(json_encode(12.0, JSON_PRESERVE_ZERO_FRACTION));var_dump(json_encode(12.0));?>

以上例程会输出：

string(4) "12.0"
string(2) "12"

注释

Note:
如果执行失败，可以通过 json_last_error() 函数来获取详细错误信息。

Note:
如果要编码的数组的键不是从0开始的数字，所有的键将会被当作字符串，并明确声明为 key-value 对。

Note:
Like the reference JSON encoder, json_encode() will generate JSON that is a simple value (that is, neither an object nor an array) if given a string, integer, float or boolean as an input value. While most decoders will accept these values as valid JSON, some may not, as the specification is ambiguous on this point.
总而言之，应该测试下 JSON decoder 能否处理 json_encode() 生成的数据。

参见

JsonSerializable
json_decode() - 对 JSON 格式的字符串进行解码
json_last_error() - 返回最后发生的错误
serialize() - 产生一个可存储的值的表示

Php/docs/function.json-encode

目录

json_encode

说明

参数

返回值

更新日志

范例

注释

参见