json_encode
(PHP 5 >= 5.2.0, PECL json >= 1.2.0)
json_encode — 对变量进行 JSON 编码
说明
string json_encode
( mixed $value
[, int $options
= 0
] )
返回 value
值的 JSON 形式
参数
value
待编码的 value
,除了resource
类型之外,可以为任何数据类型
该函数只能接受 UTF-8 编码的数据
options
由以下常量组成的二进制掩码: JSON_HEX_QUOT
,
JSON_HEX_TAG
,
JSON_HEX_AMP
,
JSON_HEX_APOS
,
JSON_NUMERIC_CHECK
,
JSON_PRETTY_PRINT
,
JSON_UNESCAPED_SLASHES
,
JSON_FORCE_OBJECT
,
JSON_UNESCAPED_UNICODE
.
返回值
编码成功则返回一个以 JSON 形式表示的 string 或者在失败时返回 FALSE
。
更新日志
版本
说明
5.4.0
options
参数增加常量:
JSON_PRETTY_PRINT
, JSON_UNESCAPED_SLASHES
, 和 JSON_UNESCAPED_UNICODE
。
5.3.3
options
参数增加常量:JSON_NUMERIC_CHECK
。
5.3.0
增加 options
参数.
范例
Example #1 A json_encode() 的例子
<?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
$a = array('<foo>',"'bar'",'"baz"','&blong&', "xc3xa9");
echo "Normal: ", json_encode($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), "nn";
$b = array();
echo "Empty array output as array: ", json_encode($b), "n";
echo "Empty array output as object: ", json_encode($b, JSON_FORCE_OBJECT), "nn";
$c = array(array(1,2,3));
echo "Non-associative array output as array: ", json_encode($c), "n";
echo "Non-associative array output as object: ", json_encode($c, JSON_FORCE_OBJECT), "nn";
$d = array('foo' => 'bar', 'baz' => 'long');
echo "Associative array always output as object: ", json_encode($d), "n";
echo "Associative array always output as object: ", json_encode($d, JSON_FORCE_OBJECT), "nn";
?>
以上例程会输出:
Normal: ["<foo>","'bar'",""baz"","&blong&","u00e9"] Tags: ["u003Cfoou003E","'bar'",""baz"","&blong&","u00e9"] Apos: ["<foo>","u0027baru0027",""baz"","&blong&","u00e9"] Quot: ["<foo>","'bar'","u0022bazu0022","&blong&","u00e9"] Amp: ["<foo>","'bar'",""baz"","u0026blongu0026","u00e9"] Unicode: ["<foo>","'bar'",""baz"","&blong&","é"] All: ["u003Cfoou003E","u0027baru0027","u0022bazu0022","u0026blongu0026","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 连续与非连续数组示例
<?php
echo "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"}"
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。
参见
JsonSerializable json_decode() - 对 JSON 格式的字符串进行编码 json_last_error() - 返回最后发生的错误