单例模式

//单例类的C++实现   class Singleton   {   private:    Singleton();//注意:构造方法私有    virtual ~Singleton();    static Singleton* instance;//惟一实例    int var;//成员变量(用于测试)   public:    static Singleton* GetInstance();//工厂方法(用来获得实例)    int getVar();//获得var的值    void setVar(int);//设置var的值   };   

//构造方法实现   Singleton::Singleton()   {    this->var = 20;    cout<<"Singleton Constructor"<<endl;   } /*Singleton::~Singleton()   {       delete instance;   }  */Singleton::~Singleton(){ if(instance != NULL) {  delete instance; }}//初始化静态成员   //Singleton* Singleton::instance=new Singleton();  Singleton* Singleton::instance=NULL;Singleton* Singleton::GetInstance()   {    if(instance == NULL) {  instance = new Singleton(); } return instance;   }   //seter && getter含数   int Singleton::getVar()   {    return this->var;   }   void Singleton::setVar(int var)   {    this->var = var;   }   //main   int main(int argc, char* argv[])   {    Singleton *ton1 = Singleton::GetInstance();    Singleton *ton2 = Singleton::GetInstance();    cout<<"ton1 var = "<<ton1->getVar()<<endl;    ton1->setVar(150);   cout<<"ton2 var = "<<ton2->getVar()<<endl;    return 0;   }