DesignPattern/SingletonPattern/SingletonPattern.cpp

#include <iostream>
using namespace std;

class Singleton {
public:
    static Singleton* Instance() {
        if (!_instance) {
            _instance = new Singleton();
        }
        return _instance;
    }
private:
    Singleton() { cout << "Singleton..." << endl; }
    static Singleton* _instance;
};
Singleton* Singleton::_instance = nullptr;

int main() {
    Singleton *singleton1 = Singleton::Instance();
    cout << singleton1 << endl;
    Singleton *singleton2 = Singleton::Instance();
    cout << singleton2 << endl;

    delete Singleton::Instance();

    return 0;
}