c++实现线程安全的单例模式

title: 单例模式
categories: [设计模式]
tags: [单例模式]

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#include 

using namespace std;

class HungrySingleton{
private:
    int count = 0;
    static HungrySingleton* instance;
    HungrySingleton() = default;
public:
    ~HungrySingleton() = default;
    static HungrySingleton* getInstance(){
        return instance;
    }
    void showMessage(){
        cout<showMessage();
    return 0;
}

#include 
#include 

using namespace std;

class LazySingleton{
private:
    static LazySingleton* instance;
    static mutex _lock;
    int count = 1;
    LazySingleton() = default;
public:
    ~LazySingleton() = default;
    static LazySingleton* getInstance(){
        
        if(instance==nullptr){
            lock_guard locker(_lock);
            if(instance== nullptr){
                instance = new LazySingleton;
            }
        }
        return instance;
    }
    void showMessage(){
        cout<showMessage();
    return 0;
}

#include 

class LazySingleton{
private:
    int count = 1;
    LazySingleton() = default;
public:
    ~LazySingleton() = default;
    static LazySingleton* getInstance(){
        
        static LazySingleton instance;
        return &instance;
    }
    void showMessage(){
        cout<showMessage();
    return 0;
}