Not get duplicates in math random

Question

I want my index to be a random number that is equal to my questions. I have a list of 33 questions which is indexed from 0-32. I have this idea that I will get random questions everytime with help of my index. This works but I still get duplicates. How do I prevent this?

 @if (questionIndex23 < 10)
        {
            <div class="app-title">
                @Questions[kuken].Category
            </div>

Here I get a random category from my list "question" with help of my index.

public void Hannes()
    {
        Random slump = new Random();
        kuken = slump.Next(1, 32);
    }

This is the method I've written to get random numbers for my index.

create a list of integers and write a function to fill it the function would work like generate a random number and store it in the list but ignore the generated number if it exist in the list and retry — Wali Khan, Jan 23 '23 at 12:10
Just shuffle a set of numbers representing the indexes of the questions and then consume that shuffled list from start to end. — Damien_The_Unbeliever, Jan 23 '23 at 12:11
Random numbers *can* be duplicated in a truly random sequence, just as a dice can return 6 more than once if you throw it 6 times. What you're looking for is shuffling. — Panagiotis Kanavos, Jan 23 '23 at 12:27
Adding to @Damien_The_Unbeliever suggestion. `Enumerable.Range(0, 32).OrderBy(_ => Random.Shared.Next()).ToList()` — Brian Parker, Jan 23 '23 at 12:51

fubo · Accepted Answer · 2023-01-23T12:21:44.507

3

Shuffle your questions

Random slump = new Random();
Questions = Questions.OrderBy(_ => slump.Next()).ToList();

before displaying them

@foreach(var question in Questions)
{
    < div class="app-title">
        @question.Category
    </div>

edited Jan 23 '23 at 12:21

answered Jan 23 '23 at 12:11

fubo

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This sadly doesn't work. It's just stuck on question number one. – carlsby Jan 23 '23 at 12:19
2

what doesn't work? The `OrderBy()` or the `foreach` – fubo Jan 23 '23 at 12:22
It displays the whole list. I want to get one question at the time. – carlsby Jan 23 '23 at 12:29
ok then you have to remember the number of asked questions `int currentQuestion = 0;` and increment it each time a qestion is asked `currentQuestion++;` and `Questions[currentQuestion ]` - wasn't clear how your question thing works – fubo Jan 23 '23 at 12:43
btw, you can do `Random.Shared.Next()` in .net7 and make it one-liner. – Alamakanambra Jan 23 '23 at 21:32
@Alamakanambra since .net6 actually. – Mark Cilia Vincenti Jan 30 '23 at 08:41

Not get duplicates in math random

1 Answers1