Question

I am currently building a sorting program. I have made three different ways to create an array: Random, In Order and Reverse. I am currently undergoing problems with the In Order and Reverse arrays. Every time an In Order array is created it starts with a 1, I am not sure how come is doing so. Also my Reverse array will display digits out of order not every time but after some clicks. How can I fix these two issues?

namespace sortingMachine
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        //Class Level Variables --------------------------------------------------------------------------------------

        Stopwatch sw = new Stopwatch();
        Random r = new Random();
        OpenFileDialog open1 = new OpenFileDialog();

        long operations = 0;
        int size;
        int max;
        int[] createArray;
        int[] sortArray;
        int[] copyArray;

        //Create Array Methods --------------------------------------------------------------------------------------

        public void RandomNumber()
        {
            size = Convert.ToInt32(textBoxSize.Text);
            max = Convert.ToInt32(textBoxMax.Text);
            createArray = new int[size];
            copyArray = new int[size];
            sortArray = new int[size];

            for (int i = 0; i < size; i++)
            {
                createArray[i] = r.Next(1, max);
            }

            textBoxResults.AppendText("-------------------------------------------------------------------------------" + Environment.NewLine + "Random" + Environment.NewLine + Environment.NewLine);

            DisplayArrays();
        }

        public void InOrder()
        {
            size = Convert.ToInt32(textBoxSize.Text);
            max = Convert.ToInt32(textBoxMax.Text);
            createArray = new int[size];
            copyArray = new int[size];
            sortArray = new int[size];

            createArray[0] = 1;

            for (int i = 1; i < size; i++)
            {
                createArray[i] = createArray[i - 1] + r.Next(1, max);
            }

            for (int i = 1; i < size; i++)
            {
                if (r.Next(1, 101) < Convert.ToInt32(textBoxPercentage.Text))
                {
                    for (int x = 1; x < size; x++)
                    {
                        createArray[x] = r.Next(1, createArray[size - 1]);
                    }
                }
            }

            textBoxResults.AppendText("-------------------------------------------------------------------------------" + Environment.NewLine + "In Order" + Environment.NewLine + Environment.NewLine);

            DisplayArrays();
        }

        public void ReverseOrder()
        {
            size = Convert.ToInt32(textBoxSize.Text);
            max = Convert.ToInt32(textBoxMax.Text);
            createArray = new int[size];
            copyArray = new int[size];
            sortArray = new int[size];

            createArray[size - 1] = 1;

            for (int i = size - 1; i > 0; i--)
            {
                createArray[i - 1] = createArray[i] + r.Next(1, max);
            }

            for (int i = size - 1; i > 0; i--)
            {
                if (r.Next(1, 101) < createArray[0])
                {
                    for (int x = size - 1; x > 0; x--)
                    {
                        createArray[x] = r.Next(1, createArray[0]);
                    }
                }
            }

            textBoxResults.AppendText("-------------------------------------------------------------------------------" + Environment.NewLine + "Reverse Order" + Environment.NewLine + Environment.NewLine);

            DisplayArrays();
        }



        private void buttonCreateArray_Click(object sender, EventArgs e)
        {

            if ((textBoxSortKey.Text != "") && (textBoxCreateKey.Text != ""))
            {
                if (radioButtonRandom.Checked == true)
                {
                    RandomNumber();
                }

                if (radioButtonInOrder.Checked == true)
                {
                    InOrder();
                }

                if (radioButtonReverseOrder.Checked == true)
                {
                    ReverseOrder();
                }
            }
            else
            {
                MessageBox.Show("Type a key into the Key textbox.");
            }
        }



    }
}

Display Results:

The order array I am not sure why it always start with one:

-------------------------------------------------------------------------------
In Order
1
2
4
6
10

There are times the reverse order array will be like this:

-------------------------------------------------------------------------------

    Reverse Order
    10
    2
    7
    6
    5

Windows Form:

Answer 1

If you look at how you are assigning values to the array you’ll see that the first element is assigned zero, but in your loop you start at the second element (i.e. 1) so you never re-assign the first element.

        createArray[0] = 1;

        for (int i = 1; i < size; i++)
        {
            createArray[i] = createArray[i - 1] + r.Next(1, max);
        }

Try writing the first element assignment like this:

        createArray[0] = r.Next(1, max);

As for your reverse function, there’s too much weirdness in there to really see what you’re trying to do. Try thinking thru it a few more times. Especially be careful with code like this: if (r.Next(1, 101) < createArray[0]) – it has random behaviour and also magic numbers in it.