C++ 单例模式

class Singleton
{
public:
    void myInfo();
    static Singleton * getInstance();
private:
    Singleton();
    ~Singleton();
    static Singleton * m_sglton ;//（此处也可直接写为静态变量）
};
Singleton* Singleton:: m_sglton  = NULL;//初始化在主线程之前
Singleton *Singleton::getInstance()
{
    if(m_sglton  == NULL)
    {
        m_sglton = new Singleton; 
    }
    return sglton;（返回对象）
}

class Singleton
{
public:
    void myInfo();
    static Singleton * getInstance();
private
     Singleton();
    ~Singleton();
:
};
Singleton *Singleton::getInstance()
{
   static Singleton siglton;
   return &siglton;
}

•   返回静态局对象的引用，由于担心发生该对象的拷贝，将其拷贝构造和赋值构造改为私有函数。
  

class Singleton
{
public:
    void myInfo();
    static Singleton &getInstance();
private:
    Singleton();
    ~Singleton();
    Singleton(const Singleton &);
    Singleton &operator =(const Singleton &);
};
Singleton &Singleton::getInstance()
{
   static Singleton siglton;
   return siglton;
}

class Singleton
{
public:
    void myInfo();
    static Singleton &getInstance();
private:
  Singleton();
    ~Singleton();
    Singleton(const Singleton &);
    Singleton &operator =(const Singleton &);
};

Singleton &Singleton::getInstance()
{
   Lock();
   static Singleton siglton;
   UnLock();
   return siglton;
}