Php/docs/function.json-encode
json_encode
(PHP 5 >= 5.2.0, PHP 7, PECL json >= 1.2.0)
json_encode — Returns the JSON representation of a value
Description
json_encode
( mixed $value
[, int $flags
= 0
[, int $depth
= 512
]] ) : string|false
Returns a string containing the JSON representation of the supplied
value
.
The encoding is affected by the supplied flags
and additionally the encoding of float values depends on the value of
serialize_precision.
Parameters
value
The
value
being encoded. Can be any type except a resource.All string data must be UTF-8 encoded.
Note:
PHP implements a superset of JSON as specified in the original » RFC 7159.
flags
Bitmask consisting of
JSON_FORCE_OBJECT
,JSON_HEX_QUOT
,JSON_HEX_TAG
,JSON_HEX_AMP
,JSON_HEX_APOS
,JSON_INVALID_UTF8_IGNORE
,JSON_INVALID_UTF8_SUBSTITUTE
,JSON_NUMERIC_CHECK
,JSON_PARTIAL_OUTPUT_ON_ERROR
,JSON_PRESERVE_ZERO_FRACTION
,JSON_PRETTY_PRINT
,JSON_UNESCAPED_LINE_TERMINATORS
,JSON_UNESCAPED_SLASHES
,JSON_UNESCAPED_UNICODE
,JSON_THROW_ON_ERROR
. The behaviour of these constants is described on the JSON constants page.depth
Set the maximum depth. Must be greater than zero.
Return Values
Returns a JSON encoded string on success or FALSE
on failure.
Changelog
Version | Description |
---|---|
7.3.0 | JSON_THROW_ON_ERROR
|
7.2.0 | JSON_INVALID_UTF8_IGNORE , and
|
7.1.0 | JSON_UNESCAPED_LINE_TERMINATORS
|
7.1.0 | serialize_precision is
used instead of precision when encoding double values. |
Examples
Example #1 A json_encode() example
<?php$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
<?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));?>
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
<?phpecho "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
<?phpvar_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"
Notes
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, int, float or bool 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().
See Also
- JsonSerializable
- json_decode() - Decodes a JSON string
- json_last_error() - Returns the last error occurred
- serialize() - Generates a storable representation of a value