Problems occur when using while loop in c#

Question

I have this code that shuffle numbers from 1 to 17 and put these numbers into textboxes
The problem occurs when using While loop the form doesn't appear and the calculations take a lot of time what is the wrong ??

this is the code that I wrote :

    private void Level_1_Load(object sender, EventArgs e)
    {

        shuffle();
    }

    private void shuffle()
    {
        Random rand = new Random();
        int randomNum;
        int[] NumArr = new int[17];
        int counter = 0;

        bool IsDuplicate = false;

        do
        {
            randomNum = rand.Next(17);
            IsDuplicate = false;

            for (int i = 0; i < NumArr.Length; i++)
            {
                if (NumArr[i] == randomNum)
                {
                    IsDuplicate = true; break;
                }
            }
            if (IsDuplicate == false)
            {
                NumArr[counter] = randomNum;
                counter++;
            }

        } while (counter < 17);


    TextBox1.Text = NumArr[0].ToString();
    TextBox2.Text = NumArr[1].ToString();
    TextBox3.Text = NumArr[2].ToString();
    TextBox4.Text = NumArr[3].ToString();
    TextBox5.Text = NumArr[4].ToString();
    TextBox6.Text = NumArr[5].ToString();
    TextBox7.Text = NumArr[6].ToString();
    TextBox8.Text = NumArr[7].ToString();
    TextBox9.Text = NumArr[8].ToString();
    TextBox10.Text = NumArr[9].ToString();
    TextBox11.Text = NumArr[10].ToString();
    TextBox12.Text = NumArr[11].ToString();
    TextBox13.Text = NumArr[12].ToString();
    TextBox14.Text = NumArr[13].ToString();
    TextBox15.Text = NumArr[14].ToString();
    TextBox16.Text = NumArr[15].ToString();
    TextBox17.Text = NumArr[16].ToString();

    }

It seems it will never gonna break the loop. Because your counter never gonna be higher then 16. After it reached to 16 it wont get increased because duplicate will not false again since array is full with values. — Eldar
– Eldar, Commented Nov 17, 2019 at 13:45
Does this answer your question? Best way to randomize an array with .NET — Heretic Monkey
– Heretic Monkey, Commented Nov 17, 2019 at 14:21

Shar1er80 · Accepted Answer · 2019-11-17 14:16:33Z

1

It's probably best that you initialize your array with the numbers you want and then shuffle them around. Something like:

using System;

public class Program
{
    public static void Main()
    {
        int[] numbers = new int[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17};
        shuffle(numbers);
        Console.WriteLine(String.Join(", ", numbers));
    }

    private static void shuffle(int[] numbers)
    {
        Random r = new Random((int)DateTime.Now.Ticks);
        for (int i = 0; i < numbers.Length; i++)
        {
            int temp = numbers[i];
            int index = r.Next(numbers.Length);
            numbers[i] = numbers[index];
            numbers[index] = temp;
        }
    }
}

RESULT (will be different on each run)

9, 16, 12, 6, 3, 5, 4, 14, 15, 11, 8, 10, 17, 1, 2, 13, 7

Fiddle Demo

answered Nov 17, 2019 at 14:16

Shar1er80

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2 Comments

Silver Hawk Over a year ago

thank you so much , you are genius , your code works perfectly

Shar1er80 Over a year ago

If this has answered your question, check the check mark next to the answer.

Tho Mai · Accepted Answer · 2019-11-17 13:57:14Z

0

You probably want to use another algorithm for filling an array with non-duplicate numbers.

For example, initialize your array with [0, 1, 2, 3, 4...] and shuffle it.

answered Nov 17, 2019 at 13:57

Tho Mai

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2 Comments

Silver Hawk Over a year ago

how can i shuffle the array without using random class ??

Tho Mai Over a year ago

Why don't you want to use the random class? To shuffle an array, iterate from 0 to 16, pick an random number between [0,16] and change the current array position with the random number's index.

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