json_encodeReturns the JSON representation of a value
&reftitle.description;
stringjson_encodemixedvalueintoptions0intdepth512
Returns a string containing the JSON representation of the supplied
value.
The encoding is affected by the supplied options
and additionally the encoding of float values depends on the value of
serialize_precision.
&reftitle.parameters;
value
The value being encoded. Can be any type except
a &resource;.
All string data must be UTF-8 encoded.
&json.implementation.superset;
options
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.
&reftitle.returnvalues;
Returns a JSON encoded &string; on success &return.falseforfailure;.
&reftitle.changelog;
&Version;&Description;7.3.0JSON_THROW_ON_ERRORoptions was added.
7.2.0JSON_INVALID_UTF8_IGNORE, and
JSON_INVALID_UTF8_SUBSTITUTEoptions were added.
7.1.0JSON_UNESCAPED_LINE_TERMINATORSoptions was added.
7.1.0
serialize_precision is
used instead of precision when
encoding double values.
5.6.6JSON_PRESERVE_ZERO_FRACTIONoptions was added.
5.5.0depth parameter was added.
5.5.0JSON_PARTIAL_OUTPUT_ON_ERRORoptions was added.
5.5.0
The return value on failure was changed from null
string to &false;.
5.4.0JSON_PRETTY_PRINT,
JSON_UNESCAPED_SLASHES, and
JSON_UNESCAPED_UNICODEoptions were added.
5.3.3JSON_NUMERIC_CHECKoptions was added.
5.3.0JSON_FORCE_OBJECT,
JSON_HEX_AMP,
JSON_HEX_APOS,
JSON_HEX_QUOT, and
JSON_HEX_TAG,
options were 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($arr);
?>
]]>
&example.outputs;
A <function>json_encode</function> example showing some options in use
',"'bar'",'"baz"','&blong&', "\xc3\xa9");
echo "Normal: ", json_encode($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"}
]]>
JSON_NUMERIC_CHECK option example
]]>
&example.outputs.similar;
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"]"
]]>
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"}"
]]>
<constant>JSON_PRESERVE_ZERO_FRACTION</constant> option example
]]>
&example.outputs;
&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;
JsonSerializablejson_decodejson_last_errorserialize