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C ++ constructor copy constructor constructor of derived classes constructor of virtual inheritanceConstructor is a special method. It is mainly used to initialize an object when an object is created, that is, assigning an initial value to the object member variable. It i
C ++ constructor amp; copy constructor amp; constructor of the derived class amp; virtual inherited Constructor Constructor is a special method. It is mainly used to initialize an object when an object is created, that is, assi
virtual, and change the previous cobject definition: Class Base{ Public :Base (){} Virtual ~ Base () = 0 }; However Code It cannot be compiled. It is usually a link error and cannot be found ~ Base () Reference (GCC Error Report ). This is because the Destructor and constructor are different from other internal functions. During calls, the compiler n
Why can't constructors be virtual functions and basic class destructor?I. Why cannot constructors be virtual functions?1. From the perspective of storage space, virtual functions correspond to a pointer to the vtable virtual function table. We all know that this pointer to vtable is actually stored in the object's memo
One, what is a virtual function?Simply put, those member functions that are modified by the virtual keyword are virtual functions. The function of virtual function, the use of professional terminology to explain is to achieve polymorphism (polymorphism), polymorphism is the interface and implementation of the separatio
suitable functions, you can define the Destructor as pure virtual, and change the previous cobject definition to: class base.{Public:Base (){}Virtual ~ Base () = 0}; However, this Code cannot be compiled. It is usually a link error and cannot be found ~ Base () Reference (GCC Error Report ). This is because the Destructor and constructor are different from other
Document directory The constructor cannot be declared as a virtual function. The Destructor can be declared as a virtual function, and sometimes it must be declared as a virtual function. The constructor cannot be declared as a virtua
someone. I. virtual functions are never called during construction and analysis. 1. Constructor 1 class transaction {// base class 2 public for all transactions: 3 transaction (); 4 virtual void logtransaction () const = 0; // make a log record of different types (log entry) 5... 6}; 7 transaction: transaction () // Implementation of the base class
See stroustrup's answer (http://www.research.att.com /~ BS/bs_faq2.html # vcall) Although calling a virtual member function in constructor is not a very common technique, studying it can deepen the understanding of the virtual function mechanism and object construction process. This problem is also different from the general intuitive understanding. Let's tak
Http://anwj336.blog.163.com/blog/static/8941520920106791516915/ 1. constructor to avoid calling virtual functions Although calling a virtual member function in constructor is not a very common technique, studying it can deepen the understanding of the virtual function mechan
The reason the constructor cannot be declared as a virtual function is:Explanation 1: the so-called virtual function is to execute only one program under polymorphism. In terms of the concept of inheritance, it is always necessary to construct a parent class object before being a subclass object, if the constructor is
1 when constructing an object, you must know the actual type of the object, and the virtual function behavior is to determine the actual type during run time. While constructing an object, the object has not yet been constructed successfully. The compiler cannot know the actual type of the object, whether it is the class itself, or a derived class of that class, or a deeper derived class. Unable to determine ...2 execution of
Virtual Method The virtual method isDelphiUse the keyword virtual to define. After a method is declared as a virtual method,ProgramYou need to dynamically determine the method to be called. Now, redefine the above method. Note that the keyword override is used to indicate method overloading.CodeAs follows: Type
In virtual inheritance, the virtual base class is initialized by the final derived class, in other words, the constructor of the final derived class must call the constructor of the virtual base class. For the final derived class, the vi
Why cannot an inline function, constructor, or static member function be a virtual function? 1> inline functions Inline functions are expanded during compilation, and virtual functions are dynamically integrated during runtime. Therefore, they cannot be defined as virtual functions. 2>
From the storage space point of viewA virtual function corresponds to a vtable pointer to a virtual function table, which we all know, but this vtable pointer is actually stored in the object's memory space.The problem comes out, assuming that the constructor is virtual. It needs vtable to be called through. But the ob
Why cannot a constructor be a virtual function?1. From the perspective of storage spaceVirtual functions correspond to a vtable. We all know that this vtable is actually stored in the object's memory space. The problem arises. If the constructor is virtual, it needs to be called through vtable, but the object has not b
1, from the storage space angleThe virtual function corresponds to a vtable, which we all know, but this vtable is actually stored in the object's memory space. The problem is that if the constructor is virtual, it needs to be called through vtable, but the object is not instantiated, that is, the memory space is not available, and the vtable cannot be found, so
1. From the perspective of storage space, virtual functions correspond to a pointer to the vtable virtual function table. We all know that this pointer to vtable is actually stored in the object's memory space. The problem arises. If the constructor is virtual, it needs to be called through vtable, but the object has n
1. From the perspective of storage space Virtual functions correspond to a vtable. We all know that this vtable is actually stored in the object's memory space. The problem arises. If the constructor is virtual, it needs to be called through vtable, but the object has not been instantiated, that is, the memory space is not available and vtable cannot be found,
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