单例模式

/****单例模式要点：一是某个类只能有一个实例；二是它必须自行创建这个实例；三是它必须自行向整个系统提供这个实例。***/#include <iostream>using namespace std;class CSingleton{    public:    static CSingleton * GetInstance()    {        if(NULL == m_pInstance)            m_pInstance = new CSingleton();        return m_pInstance;    }    static void Release()   //必须，否则会导致内存泄露    {        if(NULL != m_pInstance)        {            delete m_pInstance;            cout<<"this is CSingleton::Release()"<<endl;            m_pInstance = NULL;        }    }    protected:        CSingleton()        {            cout<<"CSingleton"<<endl;        };        static CSingleton * m_pInstance;};CSingleton* CSingleton::m_pInstance = NULL;/***class CSingleDraw:public CSingleton{public:    static CSingleDraw* GetInstance()    {        if(NULL == m_pInstance)            m_pInstance = new CSingleDraw();        return (CSingleDraw*)m_pInstance;    }protected:    CSingleDraw()    {        cout<<"CSingleDraw"<<endl;    }};***/int main(){   // CSingleDraw* s1 = CSingleDraw::GetInstance();   // CSingleDraw* s2 = CSingleDraw::GetInstance();    CSingleton *s1=CSingleton::GetInstance();    CSingleton *s2=CSingleton::GetInstance();    s2->Release(); //this is CSingleton::Release()    s1->Release();    return 0;}