C++实现单例模式

单例模式分为饿汉模式与懒汉模式，下面分别对其进行实现：

#include <iostream>
#include <vector>
#include <string>
#include <mutex>
#include <pthread.h>
using namespace std;

// 单例饿汉模式
class Singleton {
private:
    Singleton() {}
    static Singleton* instance;
public:
    static Singleton* getInstance() {
        return instance;
    }
    static void Destroy() {
        delete instance;
        instance = nullptr;
    }
};

Singleton* Singleton::instance = new Singleton();

// 单例懒汉模式
class Singleton {
private:
    Singleton() {}
    static Singleton* instance;
    static pthread_mutex_t mLock;
public:
    static Singleton* getInstance() {
        pthread_mutex_lock(&mLock);
        if (instance == nullptr) {
            instance = new Singleton();
        }
        pthread_mutex_unlock(&mLock);
        return instance;
    }
    static void Destroy() {
        pthread_mutex_lock(&mLock);
        delete instance;
        instance = nullptr;
        pthread_mutex_unlock(&mLock);
    }
};

Singleton* Singleton::instance = nullptr;
pthread_mutex_t Singleton::mLock = PTHREAD_MUTEX_INITIALIZER;

int main()
{
    Singleton* A = Singleton::getInstance();
    cout << " " << endl;
    return 0;
}