---

设计一个类，只能生成该类的一个实例

class Singleton

{

public:

    static Singleton* Instance();

protected:

    Singleton();

private:

    static Singleton* _instance;

};

 

Singleton* Singleton::Instance()

{

    if (_instance == 0)

    {

        _instance = new Singleton();

    }

    return _instance;

}

 

Singleton* sgn = Singleton::Instance();