设计模式之- 单例模式（Singleton Pattern）

#include<iostream>

using namespace std;


class Singleton{
private:
    Singleton(){};//构造函数private，防止外部构造
public:
    static Singleton * instance ;//静态数据类型用来保存唯一单例
    ~Singleton(){
        delete instance;
    }
    static Singleton* getInstance(){
        if (instance == nullptr) {
            instance = new Singleton();
        }
        return  instance;
    }
    void singletonOperation(){
        cout << "singletonOperation" << endl;
    }
};

Singleton * Singleton::instance = NULL;

int main(int argc, char **argv){
    Singleton * sg = Singleton::getInstance();
    sg->singletonOperation();
    return 0;
}