What Compile Do When An Empty Class Is Declared?
-
conclusion: when an empty class is declared, the compile will generate some members by default.
(1) default constructor;
(2) copy constructor;
(3) operator=();
(4) default destructor;
- code
// the mepty class
class Empty{
};
//euqal to following
class Empty{
public:
Empty(){};
Empty(const Empty&){};
Empty& operator=(const Empty&){return *this};
inline ~Empty(){};
};
if user declares a constructor, the compile will not generate default constructor
-
explaination: when a constrcutor is decalred in C++, the compile will not generate default constructor any more. Due to compile regards you do not need a default constructor anymore.
- code
// the mepty class
class Empty{
public:
Empty(int val):m_data(val){}
private:
int m_data;
};
//equals to following
class Empty{
public:
Empty(int val):m_data(val){}
//Empty(){};
Empty(const Empty&){};
Empty& operator=(const Empty&){return *this};
inline ~Empty(){};
};
