c++23种设计模式之单例模式

#include <stdio.h>

////c++ 23种设计模式之单例模式
//适用情况：1、唯一实
namespace DesignPattern_Singleton
{
	//第一种
	class Singleton
	{

	public:
		static Singleton*Instance()
		{

			static Singleton _instance;
			return &_instance;
		}
		void showInfo()
		{

			printf(" 我是单例模式！\n");
		}
	protected:
		Singleton(){}//屏蔽构造函数

	private:
		Singleton(const Singleton&);
		Singleton& operator=(const Singleton &);

	};
	//第二种
	class ConcreteSingleton
	{

	public:
		static ConcreteSingleton *getInstance();
		void showInfo()
		{

			printf("success!\n");
		}
	protected:
		ConcreteSingleton(){}
		~ConcreteSingleton(){}
		static ConcreteSingleton *_instance;

	};
	ConcreteSingleton *ConcreteSingleton::_instance=NULL;
	ConcreteSingleton *ConcreteSingleton::getInstance()
	{

		if(_instance==NULL)
		{

			_instance=new ConcreteSingleton();

		}
		return _instance;
	}
	//第三种
	template <class T> 
	class MySingleton
	{

	public:
		static T* getInstance()
		{

			static T _instance;
			return &_instance;
		}
		void showInfo(){
				
			printf("test success \n");
		};
	protected:
		MySingleton(){}
		~MySingleton(){}

	};
	class SubMySingleton :public MySingleton<SubMySingleton>
	{


	};

}
void main()
{
	using namespace DesignPattern_Singleton;
	Singleton *p=Singleton::Instance();

	p->showInfo();


	ConcreteSingleton *pSingleton=ConcreteSingleton::getInstance();
	pSingleton->showInfo();

	SubMySingleton *sub=SubMySingleton::getInstance();
	sub->showInfo();
}