Singleton Creation the Thread-safe Way

Listing 3: A singleton that creates an instance as a local static object

// try2.h
class Singleton
{
public:
   static Singleton& instance();
   void show_state();

protected:
   Singleton();

private:
   int state;
};

Singleton& Singleton::instance()
{
   static Singleton _instance;
   return _instance;
}