array_push adds another empty array after adding my array

Question

I was working on a way to populate an empty array.

I have this code:

$array = array();
$month = 'enero';
array_push($array, $array[$month] = array('01'));
array_push($array['enero'], '02');
print_r($array);

This returns:

Array
(
    [enero] => Array
        (
            [0] => 01
            [1] => 02
        )

    [0] => Array
        (
            [0] => 01
        )

)

The array [0] appears from nowhere and I don't know what to do. I have tried

array_push($array['enero'], '02');

But it does not work. How can I get the expected result:

Array 
( 
    [enero] => Array 
        ( 
            [0] => 01 
            [1] => 02 
        )
)

Nick · Accepted Answer · 2020-03-22 03:16:05Z

2

When in doubt, avoid array_push and just use [] notation. It has the advantage of automatically creating sub-arrays that don't exist (so no need to use $array[$month] = array();):

$array = array();
$month = 'enero';
$array[$month][] = '01';
$array[$month][] = '02';
print_r($array);

If you want to use array_push, you need to create the enero element first before attempting to push into it:

$array = array();
$month = 'enero';
$array[$month] = array();
array_push($array[$month], '01');
array_push($array[$month], '02');
print_r($array);

Output (for both pieces of code):

Array
(
    [enero] => Array
        (
            [0] => 01
            [1] => 02
        )    
)

Demo on 3v4l.org

answered Mar 22, 2020 at 3:16

Nick

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3 Comments

ggorlen Over a year ago

Out of curiosity, why do you use array() instead of []?

Nick Over a year ago

@ggorlen just personal preference. I find the [ and ] around array values can get lost in a page of code but array(...) always sticks out.

Thiagosch Purpura Over a year ago

Oh.... I thought this way would not work because the $array variable would be re-asigned in each loop itinerance. thank you.

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