Randomly generated numbers with arrays are repeated

Question

I looked everywhere but I couldn’t find anything that would solve my problem. At the moment I have this:

int[] nums5 = new int[100];

        for (int i = 0; i < nums5.Length; ++i)
        {
            int aleat5;
            do
            {
                aleat5 = r.Next(1, 99);
            } while (nums5.Contains(aleat5));
            lblNum.Text = aleat5.ToString();

However, although random numbers appear, they repeat themselves. How do I fix this?

Answer 1

As I commented, you can fill the array with the loop index (nums5[i] = i + 1) and then shuffle the array using this algorithm: https://stackoverflow.com/a/110570/5775775. This will generate an array with numbers from 1 to 100 shuffled.

The code would look like this:

int[] numeros = new int[100];

// Preenche o array com os numeros de 1 a 100
for (int i = 0; i < numeros.Length; i++) {
  numeros[i] = i + 1;
}

// Embaralha os numeros (https://stackoverflow.com/a/110570/5775775)
Random rng = new Random();
int n = numeros.Length;
while (n > 1) {
    int k = rng.Next(n--);
    int temp = numeros[n];
    numeros[n] = numeros[k];
    numeros[k] = temp;
}

Answer 2

An idea would be to use a List<int> or Queue<int> to store the numbers instead of an array, because later Voce needs to remove the "chosen element"..

With a Queue<int> that it would be something like this:

Declare the Queue out of a method/function, usually before public Form1()

Queue<int> aleatorios;

Fill the form with values, in the place where you initialize the variables or in the form constructor (inside public Form1(){})

var rnd = new Random();
aleatorios = new Queue<int>(Enumerable.Range(1, 100).OrderBy(i => rnd.Next()));

Assign a value of the label (because it will be the first element), ie, make a Dequeue...

lblNum.Text = aleatorios.Dequeue().ToString();

the Dequeue automatically removes the first element of queue which has been assigned to the label