Is array_merge perform reindexing?

Question

Suppose I have an associative array with keys that are alphabetic string, and if I merge something to this array, It will merge successfully without reindexing like

$arr1 = array('john'=>'JOHN', 'marry'=>'Marry');
$arr1 = array_merge(array('78'=>'Angela'),$arr1);
print_r($arr1);

then this will correctly merge new component to array and its output will be

Array
(
    [0] => Angela
    [john] => JOHN
    [marry] => Marry
)

But when I tried same thing like this

 $arr1 = array('34'=>'JOHN', '04'=>'Marry');
 $arr1 = array_merge(array('78'=>'Angela'),$arr1);
 print_r($arr1);

then its output is like this

Array
(
    [0] => Angela
    [1] => JOHN
    [04] => Marry
)

Can anyone describes this scenario..... Also I want my array to be like this after merging..

Array
    (
        [78] => Angela
        [34] => JOHN
        [04] => Marry
    )

How can I Achieve that??

Thanks for your reply @splash58.....but can you describe why array_merge is not doing that? — SNishant, Apr 22 '17 at 15:39
Values in the input array with numeric keys will be renumbered with incrementing keys starting from zero in the result array. - http://php.net/manual/en/function.array-merge.php — splash58, Apr 22 '17 at 15:42
Possible duplicate of [php array\_merge associative arrays](http://stackoverflow.com/questions/5233721/php-array-merge-associative-arrays) — ehymel, Apr 22 '17 at 16:30

score 2 · Answer 1 · answered Apr 22 '17 at 15:42

2

as per definition array_merge will reindex numeric indexes. a string with a numeric value is also a numeric index.

To prevent this behaviour concatenate the arrays using $arr1+$arr2

answered Apr 22 '17 at 15:42

Claudio Pinto

389
2
9

Ilia Ross · Answer 2 · 2017-04-22T15:45:22.173

1

You don't need to use array_merge() as you can simply add the arrays:

$arr1 = [
  '10' => 'Angela',
  'john' => 'JOHN',
  'marry' => 'Marry',
];

$arr2 = [
  '78' => 'Angela'
];

$arr3 = $arr2 + $arr1;

array_merge() - ... values in the input array with numeric keys will be renumbered with incrementing keys starting from zero in the result array.

edited Apr 22 '17 at 15:45

answered Apr 22 '17 at 15:39

Ilia Ross

13,086
11
53
88

Is array_merge perform reindexing?

2 Answers2