PHP random number no repeat

Question

Seems to be duplicate title, but i accessed all links and none of the pages helped me.

I have the following code:

//Check if form was submitted
if($_POST){
    $number = $_POST['number'];
    $selected_choice = $_POST['choice'];
    $next=$number+1;
    $total=4;

    //Get total number of questions
    $query="SELECT * FROM `questions` LIMIT 4";
    $results = $mysqli->query($query) or die($mysqli->error.__LINE__);
    $total=$results->num_rows;

    //Get correct choice
    $q = "select * from `choices` where question_number = $number and is_correct=1";
    $result = $mysqli->query($q) or die($mysqli->error.__LINE__);
    $row = $result->fetch_assoc();
    $correct_choice=$row['id'];



    //compare answer with result
    if($correct_choice == $selected_choice){
        $_SESSION['score']++;
    }

    if($number == $total){
        header("Location: final.php");
        exit();
    } else {
            header("Location: formular1.php?n=".$next."&score=".$_SESSION['score']);
    }
}

What i need to do, is to get a random number when form is submitted, but that number must be unique and don't repeat until session ends.

I have tried:

$number = range(1, 99);
shuffle($number);

..but i dont know how to integrate that :( Thank you!

The general idea about random is that you can get the same value twice, like a dice roll. If you don't want duplicates, the best way is to take a list of numbers, shuffle them, and take one from the list, like taking a card from a shuffled deck. — GolezTrol
– GolezTrol, Commented Feb 16, 2019 at 13:15
@GolezTrol, reading the question I have the impression the OP knows all that. — trincot
– trincot, Commented Feb 16, 2019 at 13:16
@trincot I didn't get that at first, but I guess you're right. Nevertheless, I hope the analogy still clarifies the problem for either OP or future readers, and it may help thinking about solutions as well, like "Ok, deck of cards, so I need to keep that somewhere, so I can take one every time. And oh, the deck will run out eventually!" — GolezTrol
– GolezTrol, Commented Feb 16, 2019 at 13:20
Then I will prefer to use current time value to have unique generated numbers. Check this link: stackoverflow.com/questions/10640947/…. — Rohit Mittal
– Rohit Mittal, Commented Feb 16, 2019 at 13:22

trincot · Accepted Answer · 2019-02-16 13:17:43Z

2

Your idea with a shuffled array is fine, just store it in a session variable:

session_start();
if (!isset($_SESSION["numbers"]) || !count($_SESSION["numbers"])) {
    $_SESSION["numbers"] = range(1, 99);
    shuffle($_SESSION["numbers"]);
}
$next = array_pop($_SESSION["numbers"]);

edited Feb 16, 2019 at 13:17

answered Feb 16, 2019 at 13:15

trincot

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