Design Patterns: singleton mode

Objective: the number of examples is restricted to only a

example:

#define AGT_DECLARE_SINGLETON(ClassName) \
public: \
    static ClassName *Instance();   \
private:    \
    static ClassName *m_pInstance; \
	
#define AGT_DEFINE_SINGLETON(ClassName)    \
ClassName *ClassName::m_pInstance = NULL; \
ClassName *ClassName::Instance() \
{   \
    if (NULL == m_pInstance) \
    {   \
        m_pInstance = new ClassName; \
    }   \
    return  m_pInstance;    \
}   

Manager class 
{ 
Private: 
	Manager () {} 
	
public: 
	void Show () 
	{ 
		COUT << "Success" << endl; 
	} 

public:	 
	AGT_DECLARE_SINGLETON (Manager) // singleton statement 
}; 

AGT_DEFINE_SINGLETON (Manager); // Function achieve

int main() 
{
	Manager* manager = Manager::Instance();
	manager->show();
	
	Manager* manager1 = Manager::Instance();
	Manager* manager2 = Manager::Instance();
	if(manager1 == manager2)
	{
		cout << "manager1 = manager2" << endl;
	}
	else
	{
		cout << "manager1 != manager2" << endl;
	}
	
	return 0;
}