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:
| Constant | Input | Output |
|---|---|---|
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":"
"}
