Singleton模式的C++实现

第一种:Meyer's singleton   无需显式调用destructor

class Singleton{ private: Singleton(){cout<<"Singleton constructor"<<endl;} Singleton& operator=(Singleton&);Singleton(Singleton&); virtual ~Singleton(){ //vc6.0中需要将析构函数publiccout<<"Singleton destructor"<<endl;} public: static Singleton& getInstance() { static Singleton instance; return instance; } }; int main(){Singleton& a1 = Singleton::getInstance();Singleton& b1 = Singleton::getInstance();return 0;}  

 

第二种:   需要自己调用destructor

 class Singleton{ private: Singleton(){cout<<"Singleton constructor"<<endl;} Singleton& operator=(Singleton & o){} Singleton(Singleton & o){} static Singleton *instance;virtual ~Singleton() { if(NULL!=instance) {cout<<"Singleton destructor"<<endl;//other operations, such as release memoryinstance=NULL; } } public: staticSingleton& getInstance() { if(NULL==instance) { instance=new Singleton(); } return *instance; } static void releaseInstance(){delete instance;}}; Singleton* Singleton::instance=NULL; int main(){Singleton& a2 = Singleton::getInstance();Singleton& b2 = Singleton::getInstance();Singleton::releaseInstance();return 0;}