        private void button1_Click(object sender, EventArgs e)
        {
            int[] a ={ 1, 2, 3, 4, 5 };
            modifyElement(a[1], ref a[2]);
            label1.Text = "Effect of passing array elemnts :\n" +
                "by value and by reference : " +
                " a[1] = " + a[1] + ", a[2] = " + a[2];
            label1.Text += "\n\nEffets of passing arry :";
            label1.Text += "\nBefore pass to method :";
            foreach (int i in a)
            {
              label1 .Text += "  " + i;
            }
            modifyArray(a);
            label1.Text += "\nAfter return from method :";
            foreach (int i in a)
            {
                label1.Text += "  " + i;
            }
        }
