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

    VersionDescription
    7.3.0JSON_THROW_ON_ERRORflags was added.
    7.2.0JSON_INVALID_UTF8_IGNORE, and JSON_INVALID_UTF8_SUBSTITUTEflags were added.
    7.1.0JSON_UNESCAPED_LINE_TERMINATORSflags was added.
    7.1.0serialize_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

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