abstract class Motorcycle
{
 // Anyone can call this.
 public void StartEngine() {/* Method statements here */ }

 // Only derived classes can call this.
 protected void AddGas(int gallons) { /* Method statements here */ }

 // Derived classes can override the base class implementation.
 public virtual int Drive(int miles, int speed) { /* Method statements here */ return 1; }

 // Derived classes must implement this.
 public abstract double GetTopSpeed(); 
}

class TestMotorcycle : Motorcycle
{

 public override double GetTopSpeed()
 {
  return 108.4;
 }

 static void Main()
 {

  TestMotorcycle moto = new TestMotorcycle();

  moto.StartEngine();
  moto.AddGas(15);
  moto.Drive(5, 20);
  double speed = moto.GetTopSpeed();
  Console.WriteLine("My top speed is {0}", speed);   
 }
}

public void Caller()
{
 int numA = 4;
 // Call with an int variable.
 int productA = Square(numA);

 int numB = 32;
 // Call with another int variable.
 int productB = Square(numB);

 // Call with an integer literal.
 int productC = Square(12);

 // Call with an expression that evaulates to int.
 productC = Square(productA * 3);
}

int Square(int i)
{
 // Store input argument in a local variable.
 int input = i;
 return input * input;
}

public class SampleRefType
{
 public int value;
}

public static void TestRefType()
{
 SampleRefType rt = new SampleRefType();
 rt.value = 44;
 ModifyObject(rt);
 Console.WriteLine(rt.value);
}
static void ModifyObject(SampleRefType obj)
{
 obj.value = 33;
}

class SimpleMath
{
 public int AddTwoNumbers(int number1, int number2)
 {
  return number1 + number2;
 }

 public int SquareANumber(int number)
 {
  return number * number;
 }
}

 int result = obj.AddTwoNumbers(1, 2);
result = obj.SquareANumber(result);
// The result is 9.
Console.WriteLine(result);

result = obj.SquareANumber(obj.AddTwoNumbers(1, 2));
// The result is 9.
Console.WriteLine(result);

int result = await delayTask

// using System.Diagnostics;
// using System.Threading.Tasks;

// This Click event is marked with the async modifier.
private async void startButton_Click(object sender, RoutedEventArgs e)
{
 await DoSomethingAsync();
}

private async Task DoSomethingAsync()
{
 Task<int> delayTask = DelayAsync();
 int result = await delayTask;

 // The previous two statements may be combined into
 // the following statement.
 //int result = await DelayAsync();

 Debug.WriteLine("Result: " + result);
}

private async Task<int> DelayAsync()
{
 await Task.Delay(100);
 return 5;
}

Result: 5

public Point Move(int dx, int dy) => new Point(x + dx, y + dy); 
public void Print() => Console.WriteLine(First + " " + Last);
// Works with operators, properties, and indexers too.
public static Complex operator +(Complex a, Complex b) => a.Add(b);
public string Name => First + " " + Last; 
public Customer this[long id] => store.LookupCustomer(id);