Windows Forms Calculator

double Operand1, Operand2, result, value;
string Op;
Boolean clearDisplay;


private void Digit_Click(object sender, EventArgs e)
{
    if (clearDisplay)
    {
        lblDisplay.Text = "";
        clearDisplay = false;
    }
    //namespace display(): 
    Button b = (Button)sender;
    lblDisplay.Text = lblDisplay.Text + b.Text;
}

private void btnAdd_Click(object sender, EventArgs e)
{

}

private void GetOperator_Click(object sender, EventArgs e)
{
    if (lblDisplay.Text.Length == 0)
    {
        return;
    }
    Operand1 = Convert.ToDouble(lblDisplay.Text);
    Button b = (Button)sender;
    Op = b.Text;
    lblDisplay.Text = "";
    clearDisplay = true;
}

private void btnEquals_Click(object sender, EventArgs e)
{
    if (lblDisplay.Text.Length == 0)
    {
        return;
    }
    Operand2 = Convert.ToDouble(lblDisplay.Text);
    clearDisplay = true;
    switch (Op)
    {
        case "+":

            result = Operand1 + Operand2;
            lblDisplay.Text = result.ToString();
            break;

        case "-":
            result = Operand1 - Operand2;
            lblDisplay.Text = result.ToString();
            break;

        case "*":
            result = Operand1 * Operand2;
            lblDisplay.Text = result.ToString();
            break;

        case "/":
            if (Operand2 != 0)
            {
                result = Operand1 / Operand2;
                lblDisplay.Text = result.ToString();
            }
            break;
        default:
            break;
    }
}

private void btnClear_Click(object sender, EventArgs e)
{
    lblDisplay.Text = "";

}

private void btnBackSpace_Click(object sender, EventArgs e)
{
    if (lblDisplay.Text.Length == 0)
    {
        return;
    }
    lblDisplay.Text = lblDisplay.Text.Remove(lblDisplay.Text.Length - 1, 1);
}

private void btnInverse_Click(object sender, EventArgs e)
{
    if (lblDisplay.Text.Length == 0)
    {
        return;
    }
    value = Convert.ToDouble(lblDisplay.Text);
    if (value != 0)
    {
        result = 1 / value;
        lblDisplay.Text = result.ToString();
    }
}

private void btnSign_Click(object sender, EventArgs e)
{
    if (lblDisplay.Text.Length == 0)
    {
        return;
    }
    value = Convert.ToDouble(lblDisplay.Text);
    result = -1 * value;
    lblDisplay.Text = result.ToString();
}

Courtesy : Binish Babu