CODEWITHSUNDEEP
c#listbox
Matosh
Matosh

Reputation: 33

2 x 10 random generated numbers have the same sum c#

I have 2 listboxes that i need to put 10 random generated numbers in. Then i need to calculate the sum of listbox 1 and the sum of listbox 2 and compare them to see which one is bigger. I do get different numbers in each listbox but for some reason the sum of the listboxes is always the same. How do i make it that the sum is different per listbox. this i my code at the moment.

 private void btnGo_Click(object sender, EventArgs e)
    {

        Random random = new Random();

        listBox1.Items.Clear();
        listBox2.Items.Clear();


        for (int i = 0; i < 10; i++)
        {

            int nummer = random.Next(20);
            int nummer2 = random.Next(20);
            listBox1.Items.Add(nummer);
            listBox2.Items.Add(nummer2);
        }




        if (addListbox1() > addListbox2())
        {
            textBox1.Text = "Listbox1 heeft de hoogste waarde namelijk " + Convert.ToString(addListbox1());
            listBox1.BackColor = Color.Green;
            listBox2.BackColor = Color.Red;


        }

        else
        {

            textBox1.Text = "Listbox2 heeft de hoogste waarde namelijk " + Convert.ToString(addListbox2());
            listBox1.BackColor = Color.Red;
            listBox2.BackColor = Color.Green;


        }



    }
    private int addListbox1()
    {
        int listbox1total = 0;

        for (int k = 0; k < listBox1.Items.Count;)
        {
            listbox1total += Convert.ToInt32(listBox1.Items[k++]);
        }
        return listbox1total;
    }

    private int addListbox2()
    {
        int listbox2total = 0;
        int k = 0;

        while(k < listBox2.Items.Count)
        {
            listbox2total += Convert.ToInt32(listBox1.Items[k++]);

        }
        return listbox2total;
    }

Upvotes: 2

Views: 82

Answers (1)

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186748

You have a typo (an old story of copy + paste) in the code:

listbox2total += Convert.ToInt32(listBox1.Items[k++]);

should be 

// please, notice "listBox2.Items"
listbox2total += Convert.ToInt32(listBox2.Items[k++]);

i.e. listbox2total should be the sum of listBox2.Items.

In order to avoid such errors, change the design, do not copy yourself, extract methods:

// Easiest, but not thread safe
private static Random random = new Random();

private static void FillBox(ListBox box, int count = 10) {
  box.Items.Clear();

  box.Items.AddRange(Enumerable
    .Range(0, count)
    .Select(x => (Object) random.Next(20))
    .ToArray());
}

private static int SumBox(ListBox box) {
  return box.Items
    .OfType<Object>()
    .Sum(x => Convert.ToInt32(x));
}

...

FillBox(listBox1);
FillBox(listBox2);

if (SumBox(listBox1) > SumBox(listBox2)) {
  ...
}

Upvotes: 3

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