How virtual functions can be implemented in C++?

 

 

Posted Date: 3/15/2013 6:31:11 AM | Location : United States

Ask an Expert

A: Virtual functions are implemented by a table of function pointers, called vtable. There is one entry in table per virtual function in class. This table is formed through the constructor of the class. While a derived class is constructed, its base class is constructed _rst that creates the vtable. If the derived class overrides any of base classes virtual functions, those entries into the vtable are overwritten through the derived class constructor. It is why you must never call virtual functions from a constructor: since the vtable entries for the object might not have been set up through the derived class constructor still, so you might end up calling base class implementations of those virtual functions Posted by | Posted Date: 3/15/2013 6:31:40 AM

A: Virtual functions are implemented by a table of function pointers, called vtable. There is one entry in table per virtual function in class. This table is formed through the constructor of the class. While a derived class is constructed, its base class is constructed _rst that creates the vtable. If the derived class overrides any of base classes virtual functions, those entries into the vtable are overwritten through the derived class constructor. It is why you must never call virtual functions from a constructor: since the vtable entries for the object might not have been set up through the derived class constructor still, so you might end up calling base class implementations of those virtual functions Posted by | Posted Date: 3/15/2013 6:32:48 AM

Related Discussions:- How virtual functions can be implemented in c++?, Assignment Help, Ask Question on How virtual functions can be implemented in c++?, Get Answer, Expert's Help, How virtual functions can be implemented in c++? Discussions

Write discussion on How virtual functions can be implemented in c++?
Your posts are moderated

Write your message here..

Related Questions

C++ project, project on business management project on business management

How to define a structure, How to Define a Structure? Structure declara... How to Define a Structure? Structure declarations are rather more complicated than array declarations, ever since a structure must be defined in terms of its individual members

Constant argument, Define  C o ns t a n t a r g u me n t : ... Define  C o ns t a n t a r g u me n t : T h e a r gu m e n t c a n b e a c on s t a n t a r gu m e n t .    T h e c o

#include , volume of a sphere volume of a sphere

Difference between echo and print statement, Difference between Echo and pr... Difference between Echo and print statement. print()and echo() are language constructs in PHP, both are used to output strings. Both statements are of almost same Speed. ech

Define internal static storage class - computer programming, Define Interna... Define Internal static storage class - computer programming? The Internal static variables are those that declared inside a function. The scope of the internal static variables

Hwid spoofer for windows 7, HWID Spoofer for Windows 7, 8 x64 Project De... HWID Spoofer for Windows 7, 8 x64 Project Description: I want a simple program that will spoof my hardware id. I should be able to prepare the id to spoof to in the program a

Luminous Jewels - The Polishing Game, plaese tell the full program for the ... plaese tell the full program for the above given topic with the input and output

Area under curve., write a c progrm to find area under the cuve y=f(x)  ... write a c progrm to find area under the cuve y=f(x)   #include float start_point, /* GLOBAL VARIABLES */ end_point, total_area; in

Padovan string, write a program that counts the number of occurrences of th... write a program that counts the number of occurrences of the string in the n-th padovan string p(n)   program 1 : package test.padovanstring; public class PadovanString {