C#

<br />
using System;<br />
<br />
namespace ConsoleApplication1<br />
{<br />
	class Prime<br />
	{<br />
		[STAThread]<br />
		static void Main()<br />
		{<br />
			for(int i = 2; i < 1010; ++i) if( isPrime(i) ) Console.WriteLine(i);<br />
System.Console.Read();<br />
		}<br />
<br />
		public static bool isPrime(int number)<br />
		{<br />
			if(number == 2) return true;<br />
<br />
			if(number < 2 || number % 2 == 0) return false;<br />
      <br />
			for(int i = 3; i <= (int)Math.Sqrt(number); i += 2)<br />
				if(number % i == 0) return false;<br />
<br />
			return true;<br />
		}<br />
	}<br />
}

<form runat="server" target="_blank">
  <!-- blah blah blah -->
</form>

using System;
using System.IO;
using System.Reflection;

public class Test
{
  public static void Main(string[] args)
  {
    Singleton.SayHello();
    Singleton.SayHello();

  if (!Singleton.Foo)
  {
    Console.WriteLine("Executing entry point in same AppDomain...");
    AppDomain.CurrentDomain.ExecuteAssembly(
      Assembly.GetEntryAssembly().Location);
  }

    if (AppDomain.CurrentDomain.FriendlyName != "New")
    {
      Console.WriteLine("Creating new AppDomain...");

      AppDomain domain = AppDomain.CreateDomain("New",
        AppDomain.CurrentDomain.Evidence);
      domain.ExecuteAssembly(Assembly.GetEntryAssembly().Location);
    }
  }
}

public class Singleton
{
  private TextWriter writer;
  private Singleton()
  {
    Console.WriteLine("Creating new singleton instance...");
    writer = Console.Out;
  }

  private static Singleton instance;
  private static Singleton Instance
  {
    get
    {
      if (instance == null)
        lock (typeof(Singleton))
          if (instance == null)
            instance = new Singleton();
      return instance;
    }
  }

  public static void SayHello()
  {
    Instance.writer.WriteLine("Hello, world!");
  }

  private bool foo = false;
  public static bool Foo // ?
  {
    get
  {
    if (!Instance.foo)
    {
      Instance.foo = true;
      return false;
    }

    return true;
  }
  }
}