Why php json_encode encodes two dimensional array but outputs pure array

Question

$my_array = array(
        0 => array(
                1,
                2,
                3,
            ),
        1 => array(
                1,
                2,
                3,
            ),
        2 => array(
                1,
                2,
                3,
            ),
    );
echo json_encode($my_array);

Result is this:

[[1,2,3],[1,2,3],[1,2,3]]

I thought the output should be a string of json,but here outputs a pure array,why?In other words,the result should be quoted,but why this is not.

That is a string of JSON. What were you expecting, specifically? — wavemode
– wavemode, Commented Sep 27, 2014 at 2:27
it may look like a shorthand array version, but yes, its still also json — Kevin
– Kevin, Commented Sep 27, 2014 at 2:29
when I encode one dimensional array,it is like this { "if": "foo" },but this is enclosed with square brackets,also not quoted,is this json? — user7031
– user7031, Commented Sep 27, 2014 at 2:31
@user7031 json_encode sees an array with string keys as an object, and JSON syntax surrounds objects with curly {} braces. The array in your question has only numeric keys, so it remains a JSON array with square [] brackets, and the keys remain unquoted. Look at meda's answer if you want to always encode as objects. — wavemode
– wavemode, Commented Sep 27, 2014 at 2:35
@wavemode when I quote the index,that became string keys,but json_encode still treated it as pure array,only 'JSON_FORCE_OBJECT' param can make the change? — user7031
– user7031, Commented Sep 27, 2014 at 2:43

meda · Accepted Answer · 2014-09-27 02:29:59Z

3

Use JSON_FORCE_OBJECT with json_encode()

echo json_encode($my_array, JSON_FORCE_OBJECT);

Program Output

{"0":{"0":1,"1":2,"2":3},"1":{"0":1,"1":2,"2":3},"2":{"0":1,"1":2,"2":3}}

DEMO

answered Sep 27, 2014 at 2:29

meda

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3 Comments

user7031 Over a year ago

that works,thanks,but what type of result I am having out there in the question?Is that a json too?

meda Over a year ago

yes this is valid json as an array of array , this happens because you passed plain arrays (all integer) . try switching to words and you will notice the differnce

meda Over a year ago

@user7031 did I answer your question or should I expand?

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