vtable

This question already has an answer here: Undefined reference to vtable 28 answers i have a class afporoills that helps find data in our memory managment module. (dont ask why such a wierd name i have no idea) class afporoills{ void** test(int pos); }; void** afporoills::test(int pos){ int x=(pos<<3)|1023*x; void** ret=(void**)x; if((int)ret%16) return this.test(pos+1); void* (*fp)(float, uint16__t)=x; ret=ret+(*fp)(1.0f, (uint16__t)pos); return ret; } int test(){ afporoills afporoills14; return ((char*) (uint32_t) ((uint32_t) (void*) afporoills14.test(((((uint32_t)))((char*) (void*))1)); } i

Is it possible to have inheritance with no virtual methods? The compiler is saying that the following code is not polymorphic. Example: Class A(){ int a; int getA(){return a;}; } Class B(): A(){ int b; int getB(){return b;}; } In another class we are trying to downcast from an A object to a B object: A *a; B *b = dynamic_cast<B*>(a) but this gives the following error: cannot dynamic_cast ... (source type is polymorphic) Syntax errors non-withstanding, you cannot dynamic_cast a non-polymorphic type. static_cast is the cast you would use in this case, if you know that it is in fact an object of

Possible Duplicate: why do I need virtual table? What is vtAble in C++? Got to know vtable is a virtual table which has an array of pointers to virtual functions. Is there an article with practical implementation? (Any walk through will be appreciated) doron V-tables (or virtual tables) are how most C++ implementations do polymorphism. For each concrete implementation of a class, there is a table of function pointers to all the virtual methods. A pointer to this table (called the virtual table) exists as a data member in all the objects. When one calls a virtual method, we lookup the object's

Where in memory is vtable stored? Depends on compiler. In VC++, the vtable pointer stored at the beginning of the object allocation, before any member data. (Provided your class has at least one virtual member function.) There also may be multiple vtable pointers, if your class multiply-inherits from other classes with vtables. The vtables themselves are statically allocated somewhere in your address space. Then the object layout looks like (for an instance of C): A's VTable ptr A's member variables. B's Vtable ptr B's member variables. C's member variables. for the heirarchy class A { virtual

C++ has multiple inheritance. The implementation of multiple inheritance at the assembly level can be quite complicated, but there are good descriptions online on how this is normally done (vtables, pointer fixups, thunks, etc). Java doesn't have multiple implementation inheritance, but it does have multiple interface inheritance, so I don't think a straight forward implementation with a single vtable per class can implement that. How does java implement interfaces internally? I realize that contrary to C++, Java is Jit compiled, so different pieces of code might be optimized differently, and

Following example from this link: http://developer.kde.org/documentation/books/kde-2.0-development/ch03lev1sec3.html #include <QObject> #include <QPushButton> #include <iostream> using namespace std; class MyWindow : public QWidget { Q_OBJECT // Enable slots and signals public: MyWindow(); private slots: void slotButton1(); void slotButton2(); void slotButtons(); private: QPushButton *button1; QPushButton *button2; }; MyWindow :: MyWindow() : QWidget() { // Create button1 and connect button1->clicked() to this->slotButton1() button1 = new QPushButton("Button1", this); button1->setGeometry(10

When discussing sealed classes, the term "virtual function table" is mentioned quite frequently. What exactly is this? I read about a method table a while ago (I don't remember the purpose of the purpose of this either) and a google/search on here brings up C++ related results. Thanks The C# virtual function table works basically the same as the C++ one, so any resources which describe how the C++ virtual function table works should help you pretty well with the C# one as well. For example, Wikipedia's description is not bad. The "virtual function table" or "virtual method table" is a list of