protected function btnCalculate_Click($strFormId, $strControlId, $strParameter)
{
switch ($this->lstOperation->SelectedValue) {
case 'add':
$mixResult = $this->txtValue1->Text + $this->txtValue2->Text;
break;
case 'subtract':
$mixResult = $this->txtValue1->Text - $this->txtValue2->Text;
break;
case 'multiply':
$mixResult = $this->txtValue1->Text * $this->txtValue2->Text;
break;
case 'divide':
$mixResult = $this->txtValue1->Text / $this->txtValue2->Text;
break;
default:
throw new Exception('Invalid Action');
}
$this->lblResult->Text = '<b>Your Result:</b> ' . $mixResult;
}