//懒汉式

include [HTML_REMOVED]

using namespace std;

class Singleton{

private:
static Singleton* sg;

public:
static Singleton* getInstance(){
    if(sg == nullptr){
        sg = new Singleton;
    }
    return sg;
}

};

Singleton* Singleton:: sg = nullptr;

int main(){

Singleton* a = Singleton::getInstance();
Singleton* b = Singleton::getInstance();

cout << a << "   " << b << " " << endl;

return 0;

}

//饿汉式

include [HTML_REMOVED]

using namespace std;

class Singleton{

private:
Singleton(){};
private: static Singleton* sg;
public:
static Singleton* getInstance(){
    return sg;
}

};

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

int main(){

Singleton* a = Singleton::getInstance();
Singleton* b = Singleton::getInstance();

cout << a << "   " << b << " " << endl;

return 0;

}