In C++, once a member function is declared as a virtual function in a base class, it becomes virtual in every class derived from that base class. In other words, it is not necessary to use the keyword virtual in the derived class while declaring rede…
Ordinarily, if we do not use a function, we do not need to supply a definition of the function. However, we must define every virtual function, regardless of whether it is used, bacuase compiler has no way to determine whether a virtual function is u…
There is a base class at the root of the hierarchy, from which the other class inherit, directly or indirectly. These inheriting classes are known as derived calsses. The key ideas in Object-Oriented Programming are data abstraction, inheritance and…
How can I protect derived classes from breaking when I change the internal parts of the base class? A class has two distinct interfaces for two distinct sets of clients: It has a public interface that serves unrelated classes It has a protected inter…
原文链接:http://www.drdobbs.com/cpp/standard-c-programming-virtual-functions/184403747 By Josée Lajoie and Stanley Lippman, September 01, 2000 As we gain mastery of C++, it is natural to question the rules of thumb that helped us get by in the beginning.…
Because such calls would never go to a more derived class than that of currently executing construtor or destructor. In other word, it would call the version of base class rather than that of derived classes. For example, if you have a base transacti…
13.3 How do virtual functions work in C++? 这道题问我们虚函数在C++中的工作原理.虚函数的工作机制主要依赖于虚表格vtable,即Virtual Table.当类中定义了虚函数时,一个虚表格就建立了用来保存该类的虚函数的地址.此时编译器Compiler也会在该类中增加一个虚指针vptr(Virtual Pointer),用来指向虚表格.当一个虚函数在派生类中没有被重写时,派生类中的虚表格中仍然存的是基类的虚函数的地址.当虚函数被调用时,就要到虚表格中取…
A derived class inherits all of the members of a base class except for its constructors. You must define a constructor in a derived class unless the base class has defined a default (parameterless) constructor. If you don’t define a constructor in t…
