json_encode
Returns the JSON representation of a value
&reftitle.description;
stringjson_encode
mixedvalue
intoptions0
Returns a string containing the JSON representation of
value.
&reftitle.parameters;
value
The value being encoded. Can be any type except
a resource.
This function only works with UTF-8 encoded data.
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_UNESCAPED_UNICODE.
&reftitle.returnvalues;
Returns a JSON encoded string on success &return.falseforfailure;.
&reftitle.changelog;
&Version;
&Description;
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.
&reftitle.examples;
A <function>json_encode</function> example
1, 'b' => 2, 'c' => 3, 'd' => 4, 'e' => 5);
echo json_encode($arr);
?>
]]>
&example.outputs;
A <function>json_encode</function> example showing all the options in action
',"'bar'",'"baz"','&blong&', "\xc3\xa9");
echo "Normal: ", json_encode($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";
?>
]]>
&example.outputs;
","'bar'","\"baz\"","&blong&","\u00e9"]
Tags: ["\u003Cfoo\u003E","'bar'","\"baz\"","&blong&","\u00e9"]
Apos: ["","\u0027bar\u0027","\"baz\"","&blong&","\u00e9"]
Quot: ["","'bar'","\u0022baz\u0022","&blong&","\u00e9"]
Amp: ["","'bar'","\"baz\"","\u0026blong\u0026","\u00e9"]
Unicode: ["","'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"}
]]>
Sequential versus non-sequential array example
"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)
);
?>
]]>
&example.outputs;
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"}"
]]>
&reftitle.notes;
In the event of a failure to encode, json_last_error
can be used to determine the exact nature of the error.
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.
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.
&reftitle.seealso;
JsonSerializable
json_decode
json_last_error
serialize