How to insert an array into another array in PHP?

Question

I have the following PHP Array:

$mod = array( 1 => array(), 2 => array(), 3 => array());

When I json_encode $mod, it produces this:

{"1":[],"2":[],"3":[]}

But I want to be able to do this in the following manner:

$tstarray = array();
$newaray = array(1 => array());
$newaray2 = array(2 => array());
$newaray3 = array(3 => array());
array_push($tstarray, $newaray);
array_push($tstarray, $newaray2);
array_push($tstarray, $newaray3);

When I json_encode $tstarray, it produces a result like this:

[{"1":[]},{"2":[]},{"3":[]}]

I want the second result to look like the first result. By "look" I mean the same type. Do you know what I would need to change in order to get this to be the same?

Update: What end result do I need?

If I have var x = 9 Then I need a while loop that will create the $mod variable but do it all the way from 1 => array() to 9 => array(). How would I do this?

Tommaso Belluzzo · Accepted Answer · 2017-12-28 00:52:30Z

3

$arr1 = array(1 => array());
$arr2 = array(2 => array());
$arr3 = array(3 => array());
$arr = $arr1 + $arr2 + $arr3;

print_r(json_encode($arr));

Output is:

{"1":[],"2":[],"3":[]}

This also works with nested arrays.

$arr1 = array(1 => array(1 => "A", 2 => "B"));
$arr2 = array(2 => array(1, 2, 3));
$arr3 = array(3 => array(1 => "C", 2 => "D"));
$arr = $arr1 + $arr2 + $arr3;
print_r(json_encode($arr));

Output:

{"1":{"1":"A","2":"B"},"2":[1,2,3],"3":{"1":"C","2":"D"}}

The problems appear once you start defining zero-indexed values in your arrays... at that point they will start getting json-encoded as true arrays.

REQUEST UPDATE

$arr = array();

for ($i = 1; $i < 10; ++$i)
    $arr = $arr + array($i => array());

print_r(json_encode($arr));

Output:

{"1":[],"2":[],"3":[],"4":[],"5":[],"6":[],"7":[],"8":[],"9":[]}

edited Dec 28, 2017 at 0:52

answered Dec 27, 2017 at 23:48

Tommaso Belluzzo

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5 Comments

Rixwaan Over a year ago

Will it also function as an array within an array?

Tommaso Belluzzo Over a year ago

Anyway yes, it works... but as long as you don't zero-index your arrays, otherwise they will be json-encoded as true arrays.

Tommaso Belluzzo Over a year ago

Make some tests as I did, for the moment I obtained a 100% behavior match.

Rixwaan Over a year ago

I am new to PHP, so instead of print_r if I use echo, will it be the same?

Tommaso Belluzzo Over a year ago

Absolutely: echo(json_encode($arr)) prints the same... but never base your assumption on what you print... but on the content.

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