C#

// .NET Singleton
sealed class Singleton 
{
    private Singleton() {}
    public static readonly Singleton Instance = new Singleton();
}

sealed class SingletonCounter {
    public static readonly SingletonCounter Instance = 
         new SingletonCounter();
    private long Count = 0;
    private SingletonCounter() {}
    public long NextValue() {
        return ++Count;
    }
}

class SingletonClient {
    [STAThread]
    static void Main() {
        for (int i=0; i<20; i++) {
            Console.WriteLine("Next singleton value: {0}", 
                SingletonCounter.Instance.NextValue());
        }
    }
}

private static void FindKey(RegistryKey key, string keyname)
{
   string[] values = key.GetValueNames();
   for (int j = 0; j < key.ValueCount; j++)
   {
      if (values[j] == keyname) Console.WriteLine(key.Name);
   }
   string[] subkeys = key.GetSubKeyNames();
   for (int i = 0; i < key.SubKeyCount; i++)
   {
      try 
      {
         FindKey(key.OpenSubKey(subkeys[i]), keyvalue);
      }
      catch (System.Security.SecurityException){}
   }
}

public static void Main(string[] args)
{
   FindKey(Registry.CurrentUser, "LeppieRules");
}