Question

My program, should do: In other thread write each result to global array. A main thread read from global array and put on screen.

It’t make in Windows Form Aplication. Other question, how show result in textbox step by step. Normaly, all resault is show on the end of a loop. How refresh a Form in everyone move. And how change view in textbox. Normally I see the first number – 1-, I need see last number – 199 – automatically.

I have eception:

Warning 1 Field ‘WFA_watki.Form1.tab’ is never assigned to, and
will always have its default value null

My code:

namespace WFA_watki
{
    public partial class Form1 : Form
    {
        int[] tab; //----- exception -----

        void licz()
        {
            int wynik = 0;
            for (int i = 0; i < 100; i++)
            {

                wynik =+ i;
                tab[i] = wynik;

            }

            MessageBox.Show("Fnish thread 1. result: " + wynik);


        }

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
             Thread watek1 = new Thread(licz);
             watek1.Start();

             Thread.Sleep(1000);

             for (int i=0; i < 100; i++)
             {
                 textBox1.Text += tab[i].ToString() + Environment.NewLine;
             }      


        }

    }
}

Answer 1

tab is defined but never initialised – that means you have said what it is, but never set it to anything. You then attempt to access elements in it even though you haven’t initialised it.

Try this:

int[] tab = new int[100];

I’ve given it a size of 100 because you have a loop iterating up to that value in your button1_Click function.