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This article will explain in detail what is the method of realizing the singleton model on C++. The content of the article is of high quality, so the editor shares it with you for reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Hungry man model

Class instantiation will take up memory, waste resources, high efficiency, and there is no thread safety problem.

Class Singleton {Singleton () {} static Singleton* instancepostptritspublic: static Singleton* get_instance () {return instancepostptra;}; Singleton* Singleton::m_instance_ptr = new Singleton (); int main () {Singleton* instance1 = Singleton::get_instance (); Singleton* instance2 = Singleton::get_instance (); return 0;} slob mode

Delayed loading, saving resources, low efficiency, thread safety problems.

Class Singleton {Singleton () {} static Singleton* new Singleton () {} Singleton* instance1 = Singleton::get_instance (): static Singleton* get_instance () {if (m_instance_ptr = = nullptr) m_instance_ptr = new Singleton (); return massively instanceperfect ptre;}}; Singleton* instance2 = Singleton::get_instance (); return 0;} Lock + Smart pointer

Thread safety (lock) + memory recovery (smart pointer)

# include # include # include class Singleton {public: typedef std::shared_ptr Ptr; static Ptr get_instance () {if (m_instance_ptr = = nullptr) {std::lock_guard lk (m_mutex); if (m_instance_ptr = = nullptr) m_instance_ptr = std::shared_ptr (new Singleton) } return Singleton::get_instance ();} private: Singleton () {} static Ptr instanceroomptre; static std::mutex massimutext;}; Singleton::Ptr Singleton::m_instance_ptr = nullptr;std::mutex Singleton::m_mutex;int main () {Singleton::Ptr instance1 = Singleton::get_instance (); Singleton::Ptr instance2 = Singleton::get_instance (); return 0 } Local static variable class Singleton {public: Singleton (const Singleton&) = delete; static Singleton& get_instance () {static Singleton instance; return instance;} private: Singleton () {}}; int main () {Singleton& instance1 = Singleton::get_instance (); Singleton& instance2 = Singleton::get_instance (); return 0 } this is the end of sharing about how C++ implements the singleton model. I hope the above content can be of some help and learn more knowledge. If you think the article is good, you can share it for more people to see.

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