#include <iostream>

using namespace std;

class Singleton

{

public:

    static Singleton *GetInstance()

    {

        if (m_Instance == NULL)

        {

            m_Instance = new Singleton();

            cout<<"get Singleton instance success"<<endl;

        }

        return m_Instance;

    }

private:

    Singleton(){cout<<"Singleton construction"<<endl;}

    static Singleton *m_Instance;

    // This is important

    class GC // 垃圾回收类

    {

    public:

        GC()

        {

            cout<<"GC construction"<<endl;

        }

        ~GC()

        {

            cout<<"GC destruction"<<endl;

            // We can destory all the resouce here, eg:db connector, file handle and so on

            if (m_Instance != NULL)

            {

                delete m_Instance;

                m_Instance = NULL;

                cout<<"Singleton destruction"<<endl;

                system("pause");//不暂停程序会自动退出，看不清输出信息

            }

        }

    };

    static GC gc;  //垃圾回收类的静态成员

};

Singleton *Singleton::m_Instance = NULL;

Singleton::GC Singleton::gc; //类的静态成员需要类外部初始化，这一点很重要，否则程序运行连GC的构造都不会进入，何谈自动析构

int main(int argc, char *argv[])

{

    Singleton *singletonObj = Singleton::GetInstance();

    return ;

}