初学设计模式之单例模式

 1 class Singleton
 2  {
 3  private:
 4      int data;
 5      static Singleton *singletonInstance;
 6      Singleton():data(0)
 7      {
 8 
 9      };
10      Singleton(const Singleton &singleton)
11      {
12          data=singleton.data;
13          singletonInstance=singleton.singletonInstance;
14      };
15      Singleton &operator=(const Singleton &m_operator)
16      {
17          data=m_operator.data;
18          singletonInstance=m_operator.singletonInstance;
19          return *this;
20 
21      };
22      ~Singleton();
23     
24  public:
25     static Singleton* getInstance()
26      {   
27          if (singletonInstance!=NULL)
28          {
29            singletonInstance=new Singleton;
30          }
31          return singletonInstance;
32      }
33  };
34 Singleton* Singleton::singletonInstance=NULL;
35 
36  int main()
37  { 
38      Singleton *m_singleton1=Singleton::getInstance();
39      Singleton *m_singleton2=Singleton::getInstance();
40      if (m_singleton1==m_singleton2)
41      {
42          cout<<"两个实例对象相同"<<endl;
43      }
44      else
45      {
46            cout<<"两个实例对象不相同"<<endl;
47      }
48      getchar();
49      return 0;