C++单例设计模式

#include <iostream>

using namespace std;

class Engine

{

public:

   static Engine* getInstance();

    

   void showMe();

    

private:

    Engine(){};

    Engine(constEngine &t);

   Engine& operator=(constEngine &t);

    

   static Engine *m_engine;

    

    

};

Engine*Engine::m_engine = NULL;

Engine*Engine::getInstance()

{

    

   if (NULL ==m_engine) {

       m_engine = newEngine();

    }

    

    returnm_engine;

}

voidEngine::showMe()

{

    cout <<"I am a singleton class of engine!" << endl;

}

int main()

{

    

   auto engine = Engine::getInstance();

    engine->showMe();

    

   return 0;

    

}