PHP insert index as value in array - php

Question

How can I add to a multidimensional array also the index number of the current added item?
$data_array[] = array('data_array_index' => *the index number of the this array on $data_array*, 'stuff' => 'stuff', etc.)
So when I:
print_r($data_array);
Array(
[0] => Array(
data_array_index => 0
stuff => stuff
)
[25] => Array(
data_array_index => 25
stuff => stuff
)
etc.
Thank you
EDIT
Should this work?
$data_array[] = array('data_array_index' => end($data_array)+1, 'stuff' => 'stuff', etc.)

Answer 1

You could do this:
$array = [
0 => [ "data_array_index" => 0, "stuff" => "stuff" ],
25 => [ "data_array_index" => 25, "stuff" => "stuff" ]
];
$array[] = array('data_array_index' => 0, 'stuff' => 'stuff')
end($array);
$last_id = key($array);
$array[$last_id]['data_array_index'] = $last_id;
I don't know why you want data_array_index in the array because if you put it in a foreach loop you can get the key without needing the variable.
Example:
foreach($key => $data) {
^^^^ The same as `data_array_index`
}

Answer 2

Suppose you have this array:
$data_array = [
0 => [ "data_array_index" => 0, "stuff" => "stuff" ],
25 => [ "data_array_index" => 25, "stuff" => "stuff" ]
];
Now to set a key (note the $data_array[100]):
$data_array[100] = [ "data_array_index" => 100, "stuff" => "stuff" ];

Answer 3

try this once
$arr=array(12=>array("stuff"=>"stuff1"),15=>array("stuff"=>"stuff2"));
foreach($arr as $key=>$val){
$arr[$key]['data_array_index']=$key;
}
echo "<pre>"; print_r($arr);

Answer 4

For my solution see the code below. Beware that this is a very rudimentary function now. It does not provide any fail safe or fallback. If you delete a key it will to fill the space etc.
<?php
// data array
$data_array = [];
// additional info for the array
$info_a = "Lorem Ipsum";
$info_b = "Lorem Ipsum";
// call function
addElement($data_array, $info_a);
addElement($data_array, $info_b);
// display output
echo '<pre>';
print_r($data_array);
echo '</pre>';
function addElement(&$array, $info)
{
// add info to the array
$array[] = [
'stuff'=>$info
];
// get the key of the current array
end($array);
$key = key($array);
// add this information to the array
$array[$key]['data_array_index'] = $key;
}
?>
Output would be
Array
(
[0] => Array
(
[stuff] => Lorem Ipsum
[data_array_index] => 0
)
[1] => Array
(
[stuff] => Lorem Ipsum
[data_array_index] => 1
)
)

Answer 5

Use array_walk
array_walk($data_array,function($value,$key)use($new_array) {
$value['data_array_index'] = $key;
$new_array[$key]=$value;
});
working demo: http://phpfiddle.org/main/code/p937-7cue