private void button18_Click(object sender, EventArgs e) { operation_pressed = false; equation.Text = ""; switch (operation) { case "+": result.Text = Operator.Add(value, double.Parse(result.Text)).ToString(); break; case "-": result.Text = Operator.Sub(value, double.Parse(result.Text)).ToString(); break; case "*": result.Text = Operator.Times(value, double.Parse(result.Text)).ToString(); break; case "/": if (result.Text == "0") { MessageBox.Show("Division Into Infinity ? "); } result.Text = Operator.Div(value, double.Parse(result.Text)).ToString(); break; case "sqrt": if (double.Parse(result.Text) < 0) { MessageBox.Show("See complex number i "); } result.Text = Operator.Sqrt(double.Parse(result.Text)).ToString(); break; case "sq": result.Text = Operator.PowToTwo(double.Parse(result.Text)).ToString(); break; case "1 / x": if (result.Text == "0") { MessageBox.Show("Division Into Infinity ? "); } result.Text = Operator.OneDivX(double.Parse(result.Text)).ToString(); break; default: break; } value = double.Parse(result.Text); operation = ""; }