vtable Questions

6

Nearly the final step but still some strange erros.... bash-3.2$ make g++ -Wall -c -g Myworld.cc g++ -Wall -g solvePlanningProblem.o Position.o AStarNode.o PRM.o PRMNode.o World.o SingleCircleWorl...

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Every class which contains one or more virtual function has a Vtable associated with it. A void pointer called vptr points to that vtable. Every object of that class contains that vptr which points...
Daladier asked 17/12, 2012 at 12:26

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So, while being in a ctor/dtor of a base class while doing smth with a derived class and calling member functions (including virtual), whether via this pointer or not, the function of the relevant ...
Newberry asked 15/5, 2022 at 16:51

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takeaway.o: In function `takeaway': project:145: undefined reference to `vtable for takeaway' project:145: undefined reference to `vtable for takeaway' takeaway.o: In function `~takeaway': project:...
Turpeth asked 5/10, 2011 at 17:24

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If I have a trait Foo, and some implementors Bar, Baz. impl Foo for Bar { } impl Foo for Baz { } But say I only use one of them ever as a trait object, let bar = Bar {..}; let foo: &dyn Foo =...
Cobra asked 14/10, 2021 at 16:59

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For this code: class B1{ public: virtual void f1() {} }; class D : public B1 { public: void f1() {} }; int main () { B1 *b1 = new B1(); D *d = new D(); return 0; } After compilation, t...
Dextrin asked 19/4, 2011 at 7:8

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I read this question: C++ Virtual class inheritance object size issue, and was wondering why virtual inheritance results in an additional vtable pointer in the class. I found an article here: http...
Electrophorus asked 13/8, 2019 at 17:47

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Assuming the following C++ source file: #include <stdio.h> class BaseTest { public: int a; BaseTest(): a(2){} virtual int gB() { return a; }; }; class SubTest: public BaseTest { p...
Manicure asked 7/5, 2014 at 22:33

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I have C++ program that reads a config file when the binary is executed, creates a number of child class instances based on the config file, and then periodically iterates over these instances and ...
Threadfin asked 21/3, 2020 at 0:16

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A friend of mine sent me the following challenge earlier today: Given the following code, propose an implementation of OBJECT_HAS_VTABLE so the program prints AnObject has a vtable = 0, AnObject...
Consol asked 11/5, 2011 at 20:39

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I am trying to print the address of a virtual member function. If I know which class implements the function I can write: print("address: %p", &A::func); But I want to do something like this...
Arboreous asked 18/6, 2010 at 8:29

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I'm curious if marking an existing derived C++ class as final to allow for de-virtualisation optimisations will change ABI when using C++11. My expectation is that it should have no effect as I see...
Irrigate asked 20/11, 2018 at 7:10

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I can understand why dynamic_cast does work in this case : #include <iostream> struct A{ virtual ~A() = default; }; struct B { virtual ~B() = default; }; struct C : A, B{}; void f(cons...
Chaps asked 4/9, 2018 at 16:48

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Rust's trait objects are fat pointers that contain 2 regular pointers: to data and to a vtable. The vtable is a structure containing a destructor function pointer, all trait method pointers and fin...
Hyperborean asked 24/8, 2018 at 20:22

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We all know what virtual functions are in C++, but how are they implemented at a deep level? Can the vtable be modified or even directly accessed at runtime? Does the vtable exist for all classes...
Stenotypy asked 19/9, 2008 at 3:29

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I am debugging a defect and have narrowed it down to the vtable pointer for an object being 0xdddddddd. This answer indicates that Win32 debug builds will generally set dead memory, or memory which...
Gallager asked 19/4, 2011 at 7:38

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Suppose I have the following code #include <thread> #include <iostream> #include <atomic> struct FooBase { void start(){ run_condition_ = true; t_ = std::thread([this](){ th...
Marqueritemarques asked 12/4, 2018 at 22:7

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I have a device that transmits binary data. To interpret the data I have defined a struct that matches the data format. The struct has a StuctLayoutAttribute with LayoutKind.Sequential. This works ...
Heteroousian asked 6/4, 2018 at 7:8

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1. the code class Parent { public: virtual void Foo() {} virtual void FooNotOverridden() {} }; class Derived : public Parent { public: void Foo() override {} }; int main() { Parent p1, p2;...
Gavrila asked 20/3, 2018 at 9:52

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Following example from this link: http://developer.kde.org/documentation/books/kde-2.0-development/ch03lev1sec3.html #include <QObject> #include <QPushButton> #include <iostream>...
Bismuthinite asked 2/5, 2011 at 7:41

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The problem: I have a family of objects with a common base, and I need to be able to identify the specific concrete type via an integer value. There are two obvious approaches to do that, however...
Kus asked 12/2, 2018 at 16:14

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Let say we have below program: class A { public: virtual fun(){}; }; class B:public A { public: virtual fun(){}; }; int main() { A a1; B b1; } My question is how many vtables and how many v...
Hammond asked 19/1, 2012 at 19:24

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Can someone explains how this virtual table for the different class is stored in memory? When we call a function using pointer how do they make a call to function using address location? Can we get...
Argentine asked 25/8, 2017 at 18:34

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is there any way to 'hack' or 'coerce' covariant overrides in to C#? For example: public class Alpha { public virtual Alpha DoSomething() { return AlphaFactory.GetAlphaFromSomewhere(); } } pub...
Porter asked 12/9, 2014 at 22:27

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C1, C2,... are callback classes. They derived from a common interface CBase with the callback CBase::f(). All of them override CBase::f() with final modifier. I have to register ~50 instance of an...
Cassis asked 29/8, 2017 at 8:43

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