(PHP 5 >= 5.2.0, PECL json >= 1.2.0, PHP 7)
json_encode — Returns the JSON representation of a value
Returns a string containing the JSON representation of
value.
value
The value being encoded. Can be any type except
a resource.
All string data must be UTF-8 encoded.
Note:
PHP implements a superset of JSON as specified in the original » RFC 4627 - it will also encode and decode scalar types and
NULL. RFC 4627 only supports these values when they are nested inside an array or an object.Although this superset is consistent with the expanded definition of "JSON text" in the newer » RFC 7159 (which aims to supersede RFC 4627) and » ECMA-404, this may cause interoperability issues with older JSON parsers that adhere strictly to RFC 4627 when encoding a single scalar value.
options
Bitmask consisting of 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_PRESERVE_ZERO_FRACTION,
JSON_UNESCAPED_UNICODE,
JSON_PARTIAL_OUTPUT_ON_ERROR. The behaviour of these
constants is described on the
JSON constants page.
depthSet the maximum depth. Must be greater than zero.
Returns a JSON encoded string on success or FALSE on failure.
| Version | Description |
|---|---|
| 7.1.0 | serialize_precision is used instead of precision when encoding double values. |
| 5.6.6 |
JSON_PRESERVE_ZERO_FRACTION option was added.
|
| 5.5.0 |
depth parameter was added.
|
| 5.4.0 |
JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, and JSON_UNESCAPED_UNICODE options were added.
|
| 5.3.3 |
JSON_NUMERIC_CHECK option was added.
|
| 5.3.0 |
The options parameter was added.
|
Example #1 A json_encode() example
<?php
$arr = array('a' => 1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
echo json_encode($arr);
?>
The above example will output:
{"a":1,"b":2,"c":3,"d":4,"e":5}
Example #2 A json_encode() example showing some options in use
<?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";
?>
The above example will output:
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 JSON_NUMERIC_CHECK option example
<?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)
);
?>
The above example will output something similar to:
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 Sequential versus non-sequential array example
<?php
echo "Sequential array".PHP_EOL;
$sequential = array("foo", "bar", "baz", "blong");
var_dump(
$sequential,
json_encode($sequential)
);
echo PHP_EOL."Non-sequential array".PHP_EOL;
$nonsequential = array(1=>"foo", 2=>"bar", 3=>"baz", 4=>"blong");
var_dump(
$nonsequential,
json_encode($nonsequential)
);
echo PHP_EOL."Sequential array with one key unset".PHP_EOL;
unset($sequential[1]);
var_dump(
$sequential,
json_encode($sequential)
);
?>
The above example will output:
Sequential array
array(4) {
[0]=>
string(3) "foo"
[1]=>
string(3) "bar"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string(27) "["foo","bar","baz","blong"]"
Non-sequential array
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"}"
Sequential array with one key unset
array(3) {
[0]=>
string(3) "foo"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string(33) "{"0":"foo","2":"baz","3":"blong"}"
Example #5 JSON_PRESERVE_ZERO_FRACTION option example
<?php
var_dump(json_encode(12.0, JSON_PRESERVE_ZERO_FRACTION));
var_dump(json_encode(12.0));
?>
The above example will output:
string(4) "12.0" string(2) "12"
Note:
In the event of a failure to encode, json_last_error() can be used to determine the exact nature of the error.
Note:
When encoding an array, if the keys are not a continuous numeric sequence starting from 0, all keys are encoded as strings, and specified explicitly for each key-value pair.
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.To summarise, always test that your JSON decoder can handle the output you generate from json_encode().