PHP Encoding a JSON string


Example

The json_encode function will convert a PHP array (or, since PHP 5.4, an object which implements the JsonSerializable interface) to a JSON-encoded string. It returns a JSON-encoded string on success or FALSE on failure.

$array = [
    'name' => 'Jeff',
    'age' => 20,
    'active' => true,
    'colors' => ['red', 'blue'],
    'values' => [0=>'foo', 3=>'bar'],
];

During encoding, the PHP data types string, integer, and boolean are converted to their JSON equivalent. Associative arrays are encoded as JSON objects, and – when called with default arguments – indexed arrays are encoded as JSON arrays. (Unless the array keys are not a continuous numeric sequence starting from 0, in which case the array will be encoded as a JSON object.)

echo json_encode($array);

Output:

{"name":"Jeff","age":20,"active":true,"colors":["red","blue"],"values":{"0":"foo","3":"bar"}}

Arguments

Since PHP 5.3, the second argument to json_encode is a bitmask which can be one or more of the following.

As with any bitmask, they can be combined with the binary OR operator |.

PHP 5.x5.3

JSON_FORCE_OBJECT

Forces the creation of an object instead of an array

$array = ['Joel', 23, true, ['red', 'blue']];
echo json_encode($array);
echo json_encode($array, JSON_FORCE_OBJECT);

Output:

["Joel",23,true,["red","blue"]]
{"0":"Joel","1":23,"2":true,"3":{"0":"red","1":"blue"}}

JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_HEX_QUOT

Ensures the following conversions during encoding:

ConstantInputOutput
JSON_HEX_TAG<\u003C
JSON_HEX_TAG>\u003E
JSON_HEX_AMP&\u0026
JSON_HEX_APOS'\u0027
JSON_HEX_QUOT"\u0022
$array = ["tag"=>"<>", "amp"=>"&", "apos"=>"'", "quot"=>"\""];
echo json_encode($array);
echo json_encode($array, JSON_HEX_TAG | JSON_HEX_AMP | JSON_HEX_APOS | JSON_HEX_QUOT);

Output:

{"tag":"<>","amp":"&","apos":"'","quot":"\""}
{"tag":"\u003C\u003E","amp":"\u0026","apos":"\u0027","quot":"\u0022"}
PHP 5.x5.3

JSON_NUMERIC_CHECK

Ensures numeric strings are converted to integers.

$array = ['23452', 23452];
echo json_encode($array);
echo json_encode($array, JSON_NUMERIC_CHECK);

Output:

["23452",23452]    
[23452,23452]
PHP 5.x5.4

JSON_PRETTY_PRINT

Makes the JSON easily readable

$array = ['a' => 1, 'b' => 2, 'c' => 3, 'd' => 4];
echo json_encode($array);
echo json_encode($array, JSON_PRETTY_PRINT);

Output:

{"a":1,"b":2,"c":3,"d":4}
{
    "a": 1,
    "b": 2,
    "c": 3,
    "d": 4
}

JSON_UNESCAPED_SLASHES

Includes unescaped / forward slashes in the output

$array = ['filename' => 'example.txt', 'path' => '/full/path/to/file/'];
echo json_encode($array);
echo json_encode($array, JSON_UNESCAPED_SLASHES);

Output:

{"filename":"example.txt","path":"\/full\/path\/to\/file"}
{"filename":"example.txt","path":"/full/path/to/file"}

JSON_UNESCAPED_UNICODE

Includes UTF8-encoded characters in the output instead of \u-encoded strings

$blues = ["english"=>"blue", "norwegian"=>"blå", "german"=>"blau"];
echo json_encode($blues);
echo json_encode($blues, JSON_UNESCAPED_UNICODE);

Output:

{"english":"blue","norwegian":"bl\u00e5","german":"blau"}
{"english":"blue","norwegian":"blå","german":"blau"}
PHP 5.x5.5

JSON_PARTIAL_OUTPUT_ON_ERROR

Allows encoding to continue if some unencodable values are encountered.

$fp = fopen("foo.txt", "r");
$array = ["file"=>$fp, "name"=>"foo.txt"];
echo json_encode($array); // no output
echo json_encode($array, JSON_PARTIAL_OUTPUT_ON_ERROR);

Output:

{"file":null,"name":"foo.txt"}
PHP 5.x5.6

JSON_PRESERVE_ZERO_FRACTION

Ensures that floats are always encoded as floats.

$array = [5.0, 5.5];
echo json_encode($array);
echo json_encode($array, JSON_PRESERVE_ZERO_FRACTION);

Output:

[5,5.5]
[5.0,5.5]
PHP 7.x7.1

JSON_UNESCAPED_LINE_TERMINATORS

When used with JSON_UNESCAPED_UNICODE, reverts to the behaviour of older PHP versions, and does not escape the characters U+2028 LINE SEPARATOR and U+2029 PARAGRAPH SEPARATOR. Although valid in JSON, these characters are not valid in JavaScript, so the default behaviour of JSON_UNESCAPED_UNICODE was changed in version 7.1.

$array = ["line"=>"\xe2\x80\xa8", "paragraph"=>"\xe2\x80\xa9"];
echo json_encode($array, JSON_UNESCAPED_UNICODE);
echo json_encode($array, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_LINE_TERMINATORS);

Output:

{"line":"\u2028","paragraph":"\u2029"}
{"line":"
","paragraph":"
"}