textbox array จะสร้าง และ เก็บไว้ใน Array ได้อย่างไรครับ

string[] arrCourse = new string[5];

        TextBox a = new TextBox();
        TextBox b = new TextBox();
        for (int i = 0; i < 5; i++)
        {
            b = (TextBox)a.FindControl("txtTest1");
            Response.Write(b.ToString());
            arrCourse[i] = b.Text;
            Response.Write(arrCourse[i]);
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            TextBox a = null;
            for (int i = 0; i < 5; i++)
            {
                a = new TextBox() ;
                a.ID = "txt" + Convert.ToString(i);
                a.Text = "Hello - " + Convert.ToString(i);
                PanelTextBox.Controls.Add(a); //PanelTextBox == ASP.NET Standard Control Panel
            }
            TextBox b = (TextBox)Page.FindControl("txt4");
            if (b !=null ) {
                Response.Write("<b>" + b.Text +"</b>"); //Result Hello - 4
            }
        }

        protected void Page_Load(object sender, EventArgs e)
        {            
            TextBox a = null;
            for (int i = 0; i < 5; i++)
            {
                a = new TextBox() ;
                a.ID = "txt" + Convert.ToString(i);
                a.Text = "Hello - " + Convert.ToString(i);
                PanelTextBox.Controls.Add(a); //PanelTextBox == ASP.NET Standard Control Panel
            }
            TextBox b = (TextBox)Page.FindControl("txt4");
            if (b !=null ) {
                Response.Write("<b>" + b.Text +"</b>"); //Result Hello - 4
                //TextBox Array
                TextBox c = (TextBox)PanelTextBox.Controls[4];
                Response.Write("<b>" + c.Text +"</b>"); //Result Hello - 4
            }
        }