Returns the JSON representation of a value

# json_encode

(PHP 5 >= 5.2.0, PHP 7, PHP 8, 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`. If the parameter is an array or object, it will be serialized recursively.

If a value to be serialized is an object, then by default only publicly visible properties will be included. Alternatively, a class may implement JsonSerializable to control how its values are serialized to JSON.

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` `flags` was added.
7.2.0 | `JSON_INVALID_UTF8_IGNORE`, and `JSON_INVALID_UTF8_SUBSTITUTE` `flags` were added.
7.1.0 | `JSON_UNESCAPED_LINE_TERMINATORS` `flags` was added.
7.1.0 | serialize_precision is used instead of precision when encoding float 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 flags 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"

### 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
- json_last_error_msg() - Returns the error string of the last json_validate(), json_encode() or json_decode() call
- serialize() - Generates a storable representation of a value

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