private void rbGPA_CheckedChanged(object sender, EventArgs e)
 {
     calculationPlanner = new CalculationPlanner();
     calculationPlanner.SetStrategy(new GPA(int.Parse(txtSID.Text)));
     if (rbGPA.Checked)
     {
         lblResult.Text = "Your GPA is " + calculationPlanner.GetResult().ToString() + ".";
     }
     lblResult.Visible = true;
 }
 private void rbPercentage_CheckedChanged(object sender, EventArgs e)
 {
     calculationPlanner = new CalculationPlanner();
     calculationPlanner.SetStrategy(new Percentage(int.Parse(txtSID.Text)));
     if (rbPercentage.Checked)
     {
         lblResult.Text = "You have got " + calculationPlanner.GetResult().ToString() + "% marks.";
     }
     lblResult.Visible = true;
 }