Accessing Form's Control from another class C#

Question

I\'m a newbie in c# and visual studio, but not programming in general. I searched for answer to my question for 3 days and I found plenty of them, but for some weird reason

Answer 1

Try this:

public partial class Form3 : Form
{
    /* Code from question unchanged until `button1_Click` */

    private void button1_Click(object sender, EventArgs e)
    {
        a.b(this);
    }
}

public class a
{       
    public static void b(Form3 form3)
    {
        form3.setCodes = "abc123";
    }
}

This passes the current instance of the form to the other class so that it can update the setCodes property. Previously you were creating a new form instance rather than updating the current form.