cpp-singleton

class Singleton {
public:
static Singleton* getInstance(){
    if (m_sInstance == 0)
    {
        m_sInstance = new Singleton();
    }
    return m_sInstance;
}
static void releaseInstance(){
    if(nullptr != m_sInstance)
    {
        delete m_sInstance;
        m_sInstance = nullptr;
    }
}

    /* more (non-static) functions here */

private:
    Singleton();                            // ctor hidden
    Singleton(Singleton const&);            // copy ctor hidden
    Singleton& operator=(Singleton const&){ return *m_sInstance; }; // assign op. hidden
    ~Singleton();                           // dtor hidden

    static Singleton* m_sInstance;
};

/* Null, because instance will be initialized on demand. */
Singleton* Singleton::m_sInstance = 0;

Singleton* Singleton::getInstance()
{
    if (m_sInstance == 0)
    {
        m_sInstance = new Singleton();
    }
    return m_sInstance;
}

Singleton::Singleton()
{}

int main()
{
    //new Singleton(); // Won't work
    Singleton* s = Singleton::getInstance(); // Ok
    Singleton* r = Singleton::getInstance();

    /* The addresses will be the same. */
    std::cout << s << std::endl;
    std::cout << r << std::endl;
}