static void Main(string[] args)
{
// create a new instance of the Calculator class
DerivedCalc calc = new DerivedCalc();
// subscribe to the event in the calaculator class
calc.CalculationPerformedEvent += HandleEvent;
// perform a calculation
calc.CalculateProduct(20, 72);
// wait for input before exiting
Console.WriteLine("Press enter to finish");
Console.ReadLine();
}
static void Main(string[] args)
{
// create an instance of the derived class
DerivedCalc calc = new DerivedCalc();
// upcast to the base type
BaseCalc bCalc = calc;
// upcast the dervied type to the interface type
ICalculator iCalc = calc;
// call the method defined by the interface and
// print out the results
int result = iCalc.CalculateSum(10, 10);
Console.WriteLine("Result: {0}", result);
// wait for input before exiting
Console.WriteLine("Press enter to finish");
Console.ReadLine();
}