(PHP 5 >= 5.2.0, PHP 7, PHP 8, PECL json >= 1.2.0)
json_encode — 對變量進(jìn)行 JSON 編碼
返回字符串,包含了 value 值 JSON 形式的表示。
編碼受傳入的 options 參數影響,此外浮點(diǎn)值的編碼依賴(lài)于 serialize_precision。
value
待編碼的 value ,除了 資源(resource)
類(lèi)型之外,可以為任何數據類(lèi)型。
所有字符串數據的編碼必須是 UTF-8。
注意:
PHP 實(shí)現了 JSON 的一個(gè)超集,參考 ? RFC 7159.
options
由以下常量組成的二進(jìn)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(guān)于 JSON 常量詳情參考
JSON 常量頁(yè)面。
depth設置最大深度。 必須大于0。
成功則返回 JSON 編碼的 string 或者在失敗時(shí)返回 false 。
| 版本 | 說(shuō)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(jìn)行編碼時(shí),使用 serialize_precision 代替 precision。 |
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(huì )輸出:
{"a":1,"b":2,"c":3,"d":4,"e":5}
示例 #2 json_encode() 函數中 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(huì )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(lèi)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"]"
示例 #4 連續與非連續數組示例
<?php
echo "連續數組".PHP_EOL;
$sequential = array("foo", "bar", "baz", "blong");
var_dump(
$sequential,
json_encode($sequential)
);
echo PHP_EOL."非連續數組".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(gè)連續數組值的方式產(chǎn)生的非連續數組".PHP_EOL;
unset($sequential[1]);
var_dump(
$sequential,
json_encode($sequential)
);
?>
以上例程會(huì )輸出:
連續數組
array(4) {
[0]=>
string(3) "foo"
[1]=>
string(3) "bar"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string(27) "["foo","bar","baz","blong"]"
非連續數組
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(gè)連續數組值的方式產(chǎn)生的非連續數組
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(huì )輸出:
string(4) "12.0" string(2) "12"
注意:
如果執行失敗,可以通過(guò) json_last_error() 函數來(lái)獲取詳細錯誤信息。
注意:
如果要編碼的數組的鍵不是從0開(kāi)始的數字,所有的鍵將會(huì )被當作字符串,并明確聲明為 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() 生成的數據。