virtual constructor

class A{public: A() { Print(); } virtual void Print() { printf("A is constructed.\n"); }}; class B: public A{public: B() { Print(); } virtual void Print() { printf("B is constructed.\n"); }}; int _tmain(int argc, _TCHAR* argv[]){ A* pA = new B(); dele

Blog migrated to: http://kulv.sinaapp.com/ The reason why the base class constructor calls the virtual function is not the problem of the derived class We know that the compiler inserts a lot of code in the constructor of the class, such as exception security, settings of the virtual function table pointer, and cons

Class B {public: Virtual void M1 (); Virtual void m2 () ;}; Class D: Public B {virtual void M1 ();} One day I took a written test by a large company. When I encountered this problem, I came back and looked at the C ++ textbooks and online materials to find answers. The answer is as follows: Dynamic binding of C ++ is implemented using vtable (

Take a look at the following code and ask whether print calls the base class or the version of the derived class?The answer is the base class...Maybe everyone will be surprised. Isn't print a virtual function? Why not call the version of the derived class? First, when defining an object of A derived classThe execution of base class constructor is earlier than that of derived class.Constructor,Therefore, whe

Yesterday, when the written test encountered a very interesting topic, the general following:Classparent{public:parent () { doit (); }~parent () {doit ();} virtualvoiddoit () { coutThe case of calling virtual functions in a constructor was not previously written in the project, which is generally not allowed, increasing the complexity of the code (see effective C + + clause 9). Remember that the order of c

1#include 2 using namespacestd;3 4 classBase15 {6 Public:7 Base1 ()8 {9cout "class Base1"Endl;Ten } One }; A - classBase2 - { the Public: - Base2 () - { -cout "class Base2"Endl; + } - }; + A classLevel1: PublicBase2,Virtual PublicBase1 at { - Public: - Level1 () - { -cout "class Level1"Endl; - } in }; - to classLevel2: PublicBase2,Virtual PublicBase1 + { - Public: the Level2

created.2. The method is called only once when an object is created. In java, this method is called the constructor. Role of constructor: Initialize the object, and initialize the property value when the object is created. Create a constructor: 1. the constructor does not return a type. The method name and class nam

default constructor A for B's synthesis of constructor classes. 3. classes with virtual functions For classes with virtual functions, the compiler synthesize a virtual table that stores virtual function pointers as needed.4.

Each class has only one destructor and one assignment function, but it can have multiple constructors (one copy constructor, others called ordinary constructors). For any class A, if you do not write the above functions, the C + + compiler will automatically generate four default functions for a, for example:A (void);//Default parameterless constructorA (const aa);//Default copy constructor~a ();//Default d

parameter, they represent post-operations. Not all operators can be reloaded. Most operators can be reloaded, ::,?, :,. Cannot be reloaded. 6. sizeof questions about classes The empty class will also be instantiated, And the compiler will implicitly Add a byte to the class, so the sizeof () Result of the empty class is 1; sizeof () is used to calculate the length of the string and contains "\ 0 ", the length of strlen () does not include "\ 0 ". Constructor