Question

I am basically just wondering how can I make this while loop repeat continuously forever? I just can’t figure out how to do it. once it reaches the end of the string it throws an exception. I have tried goto but it didn’t work idk if i was just using it in the wrong play or what but i could get it work.

    private void checkBox2_CheckedChanged(object sender, EventArgs e)
    {
        if (this.checkBox2.Checked)
        {
            int startIndex = 0;
            string str = "hiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii";
            int length = str.Length;
            while (true)
            {
                Application.DoEvents();
                Thread.Sleep(200);
                startIndex++;
                string str2 = str.Substring(startIndex, 15);
                label2.Text = str2;
                if (startIndex == length)
                {
                    startIndex = 0;
                }

Answer 1

The last valid index in a string (or any array or list or collection) is always the length – 1, not length. Furthermore, since you are taking a substring of length 15, you actually want to stop 15 characters before the end. You’ll want to change your if statement to be

if(startIndex == length - 16)
    startIndex = 0;