private void button3_Click(object sender, EventArgs e)
 {
     h.edit_course_data(textBox5.Text);
     listBox1.Items.Add(h.s1);
     listBox1.Items.Add(h.s2);
     listBox1.Items.Add(h.s3);
     listBox1.Items.Add(h.s4);
     listBox1.Items.Add(h.s5);
     listBox1.Items.Add(h.s6);
 }
        private void button2_Click_1(object sender, EventArgs e)
        {
            Admin   h            = new Admin();
            courses m            = new courses();
            int     course_index = h.edit_course_data(textBox5.Text);

            if (checkBox1.Checked == true)
            {
                m.course_name = textBox1.Text;
            }
            else
            {
                m.course_name = " ";
            }
            if (checkBox2.Checked == true)
            {
                m.pre_required_courses = textBox2.Text;
            }
            else
            {
                m.pre_required_courses = " ";
            }
            if (checkBox3.Checked == true)
            {
                m.max_num_of_students = textBox3.Text;
            }
            else
            {
                m.max_num_of_students = " ";
            }
            if (checkBox4.Checked == true)
            {
                m.credit_hours = textBox4.Text;
            }
            else
            {
                m.credit_hours = " ";
            }
            h.edit_course(course_index, m);
            MessageBox.Show("Done !");
        }