Create json file out of a multidimensional array

Question

I have a multi dimensional array that consists of 3 arrays inside. See below my minimum runnable example:

<?php

$array1 = array("Bitcoin", "Ethereum", "Bitcoin Cash");
$array2 = array("BTC", "ETH", "BTC");
$array3 = array("10000", "3000", "6666");


//Multi Dimensional Array
$multi = array($array1, $array2, $array3);
print_r($multi);

foreach($multi as $k =>$a){
  $multi[$k] = json_decode(json_encode($a));
}

print_r($multi);

// $json_data = json_encode($multi);
file_put_contents('data/myfile.json', $multi);

However, I get the following output in my output file:

ArrayArrayArray

Any suggestions how to get the data like the following:

{
"Bitcoin", 
"BTC", 
"10000"
},
{
"Ethereum", 
"ETH", 
"3000"
},
{
"Bitcoin Cash", 
"BTC", 
"6666"
},

Does all three arrays always contain the same amount of items as each other? — M. Eriksson
– M. Eriksson, Commented Dec 8, 2017 at 13:19
Btw, the json you want is invalid. {} are for objects { key: 'value', key2: 'value2', ... } while [] is for arrays ['item1', 'item2', ...] — M. Eriksson
– M. Eriksson, Commented Dec 8, 2017 at 13:21

M. Eriksson · Accepted Answer · 2017-12-08 13:39:38Z

1

First off, your expected result isn't valid json. It should be arrays [] instead of {}.

Below is how you can format the data like you want it.
However, it assumes that the three arrays always are of equal length:

$array1 = array("Bitcoin", "Ethereum", "Bitcoin Cash");
$array2 = array("BTC", "ETH", "BTC");
$array3 = array("10000", "3000", "6666");

$new = [];

// Restructure your array to get one item from each array
foreach ($array1 as $index => $value) {
    $new[] = [
        $value,
        $array2[$index],
        $array3[$index]
    ];
}

$multi = json_encode($new);

This would produce the format you want, but in valid json format:

[
    [
        "Bitcoin",
        "BTC",
        "10000"
    ],
    [
        "Ethereum",
        "ETH",
        "3000"
    ],
    [
        "Bitcoin Cash",
        "BTC",
        "6666"
    ]
]

Demo: https://3v4l.org/39kuA

edited Dec 8, 2017 at 13:39

answered Dec 8, 2017 at 13:32

M. Eriksson

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Comments

JerzySBG · Accepted Answer · 2017-12-08 13:35:40Z

1

{
"Bitcoin", 
"BTC", 
"10000"
},
{
"Ethereum", 
"ETH", 
"3000"
},
{
"Bitcoin Cash", 
"BTC", 
"6666"
},

Is not valid JSON format. '{' and '}' means that it's map (object), so there must be 'key:value' rows like:

{
0: "Bitcoin"
}

Proper JSON for array uses '[' and ']'.

<?php
$array1 = array("Bitcoin", "Ethereum", "Bitcoin Cash");
$array2 = array("BTC", "ETH", "BTC");
$array3 = array("10000", "3000", "6666");

//Multi Dimensional Array
$multi = array();
foreach($array1 as $key => $v) {
    $multi[] = [$array1[$key], $array2[$key], $array3[$key]];
}

file_put_contents('data/myfile.json', json_encode($multi));

Produces:

[["Bitcoin","BTC","10000"],["Ethereum","ETH","3000"],["Bitcoin Cash","BTC","6666"]]

Formated:

[
    [
        "Bitcoin",
        "BTC",
        "10000"
    ],
    [
        "Ethereum",
        "ETH",
        "3000"
    ],
    [
        "Bitcoin Cash",
        "BTC",
        "6666"
    ]
]

edited Dec 8, 2017 at 13:35

answered Dec 8, 2017 at 13:16

JerzySBG

1098 bronze badges

4 Comments

M. Eriksson Over a year ago

That's not the result the OP is asking for, though.

JerzySBG Over a year ago

Tags are 'php json multidimensional-array', not 'php weird-format miltidimensional-array'. He wanted to format PHP to JSON arrays, so I did that. Updated answer with information about proper format.

M. Eriksson Over a year ago

That's not what I mean. I'm 100% game on the invalid json. But look at the data inside. The OP wants to combine the three arrays.

JerzySBG Over a year ago

Ops. Code fixed.

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