private void btnShowResult_Click(object sender, EventArgs e) { Class1 compute = new Class1(); if (txtFirstNumber.Text == String.Empty) { MessageBox.Show("First Number cannot be empty"); txtFirstNumber.Focus(); return; } if (txtSecondNumber.Text == String.Empty) { MessageBox.Show("Second Number cannot be empty"); txtSecondNumber.Focus(); return; } compute.FirstNumber = Convert.ToDouble(txtFirstNumber.Text); compute.SecondNumber = Convert.ToDouble(txtSecondNumber.Text); MessageBox.Show("The public result is: " + Convert.ToString(compute.ShowResult())); txtSecondNumber.Text = String.Empty; txtFirstNumber.Text = String.Empty; }