Array push only works when array is predefined with value [duplicate]

Question

I am looking to create an array that keeps growing with one random number every time the PHP scripts runs. If I secure that the [$_SESSION["my_array"] has a value predefined then it works with increase per each script round.

However, if I do not pre-define the above mentioned array, then a random number is being created but the array does not grow in amount of stored digits.

Question: Is there a way of avoiding the need of populating the array at start? I would like the array to start with being empty.

<pre>

    <a href="session_destroy.php">Destroy session</a>

    <?php
        session_start();

        $_SESSION["my_array"] ?? [];
        $my_array = $_SESSION["my_array"];

        $new_random_value = rand(1, 6);

        array_push($my_array, $new_random_value);

        $_SESSION["my_array"] = $my_array;


        var_dump($my_array);

        var_dump($_SESSION);

    ?>

My [destroy_session] file:

<?php

    session_start();
    $_SESSION = array();
    session_destroy();

    var_dump($_SESSION);

I don't know what your'e asking but you can't have any output/html before your session_start — AbraCadaver
– AbraCadaver, Commented Jun 24, 2019 at 15:09
Try to assign session's array with $_SESSION["my_array"] = $_SESSION["my_array"] ?? []; — Cristiano Casciotti
– Cristiano Casciotti, Commented Jun 24, 2019 at 15:11
@CristianoCasciotti Your suggestion solves my issues. If you could please move your comment into an answer and add a line explaining why your suggestion works, I will go ahead and approve the answer. — Toolbox
– Toolbox, Commented Jun 24, 2019 at 15:16
This question is effectively a typo question (apart from being a mega-duplicate) because the asker knows how to write an assignment declaration ... they just failed to do so in this one instance. — mickmackusa
– mickmackusa ♦, Commented Feb 26 at 10:06

Francesco Casula · Accepted Answer · 2019-07-11 08:04:33Z

2

You're not initializing the session array, you have to initialize it like this:

$_SESSION["my_array"] = $_SESSION["my_array"] ?? [];

Otherwise you don't have a start value in your array, and that's the reason why your push doesn't grow the array.

edited Jul 11, 2019 at 8:04

Francesco Casula

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answered Jun 24, 2019 at 15:27

Cristiano Casciotti

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Comments

Beneris · Accepted Answer · 2019-06-24 15:19:19Z

0

<?php
    session_start();

    $my_array = $_SESSION["my_array"];
    if(!is_array($my_array)) {
        $my_array = array();
    }

    $new_random_value = rand(1, 6);
    array_push($my_array, $new_random_value);
    $_SESSION["my_array"] = $my_array;

    var_dump($my_array);
    var_dump($_SESSION);

?>

answered Jun 24, 2019 at 15:19

Beneris

6474 silver badges13 bronze badges

1 Comment

mickmackusa Feb 26 at 9:49

if(!is_array($my_array)) { is DEFINITELY not how you check if a variable is declared.

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