json_encode
(PHP 5 >= 5.2.0, PHP 7, PHP 8, PECL json >= 1.2.0)
json_encode — 對變數進行 JSON 編碼
參數
-
value -
待編碼的
value，除了 資源(resource) 型別之外，可以為任何數據型別。所有字串數據的編碼必須是 UTF-8。
注意:
PHP 實現了 JSON 的一個超集，參考 » RFC 7159.
-
options -
由以下常量組成的二進制掩碼：
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。 關於 JSON 常量詳情參考 JSON 常量頁面。 -
depth -
設定最大深度。 必須大於0。
返回值
成功則返回 JSON 編碼的 string 或者在失敗時返回 false 。
更新日誌
| 版本 | 說明 |
|---|---|
| 7.3.0 |
options 參數新增
JSON_THROW_ON_ERROR
常量。
|
| 7.2.0 |
options 參數新增
JSON_INVALID_UTF8_IGNORE 和
JSON_INVALID_UTF8_SUBSTITUTE
常量。
|
| 7.1.0 |
options 參數新增
JSON_UNESCAPED_LINE_TERMINATORS
常量。
|
| 7.1.0 | 對 Double 的值進行編碼時，使用 serialize_precision 代替 precision。 |
範例
示例 #1 json_encode() 例子
<?php
$arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);
echo json_encode($arr);
?>
以上例程會輸出：
{"a":1,"b":2,"c":3,"d":4,"e":5}
示例 #2 json_encode() 函式中 options 參數的用法
<?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";
?>
以上例程會輸出：
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"}
示例 #3 選項 JSON_NUMERIC_CHECK 例子
<?php
echo "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)
);
?>
以上例程的輸出類似於：
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"]"
示例 #4 連續與非連續陣列示例
<?php
echo "連續陣列".PHP_EOL;
$sequential = array("foo", "bar", "baz", "blong");
var_dump(
$sequential,
json_encode($sequential)
);
echo PHP_EOL."非連續陣列".PHP_EOL;
$nonsequential = array(1=>"foo", 2=>"bar", 3=>"baz", 4=>"blong");
var_dump(
$nonsequential,
json_encode($nonsequential)
);
echo PHP_EOL."刪除一個連續陣列值的方式產生的非連續陣列".PHP_EOL;
unset($sequential[1]);
var_dump(
$sequential,
json_encode($sequential)
);
?>
以上例程會輸出：
連續陣列
array(4) {
[0]=>
string(3) "foo"
[1]=>
string(3) "bar"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string(27) "["foo","bar","baz","blong"]"
非連續陣列
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"}"
刪除一個連續陣列值的方式產生的非連續陣列
array(3) {
[0]=>
string(3) "foo"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string(33) "{"0":"foo","2":"baz","3":"blong"}"
示例 #5 選項 JSON_PRESERVE_ZERO_FRACTION 的例子
<?php
var_dump(json_encode(12.0, JSON_PRESERVE_ZERO_FRACTION));
var_dump(json_encode(12.0));
?>
以上例程會輸出：
string(4) "12.0" string(2) "12"
註釋
注意:
如果執行失敗，可以通過 json_last_error() 函式來獲取詳細錯誤資訊。
注意:
如果要編碼的陣列的鍵不是從0開始的數字，所有的鍵將會被當作字串，並明確聲明為 key-value 對。
注意:
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.總而言之，應該測試下 JSON decoder 能否處理 json_encode() 產生的數據。
參見
- JsonSerializable
- json_decode() - 對 JSON 格式的字串進行解碼
- json_last_error() - 返回最後發生的錯誤
- serialize() - 產生一個可儲存的值的表示