vtable

I know it sounds silly and I know that C is not an Object Oriented Language. But is there any way that dynamic method dispatching can be achieved in C? I thought about function pointers but don't get the entire idea. How could I implement this? As others have noted, it is certainly possible to implement this in C. Not only is it possible, it is a fairly common mechanism. The most commonly used example is probably the file descriptor interface in UNIX. A read() call on a file descriptor will dispatch to a read function specific to the device or service that provided that file descriptor (was it

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: A *b = new B(); printf("address: %p", &b->func); printf("address: %p", &b->A::func); However this does not compile. Is it possible to do something like this, perhaps looking up the address in the vtable at runtime? Lukas W Currently there is no standard way of doing this in C++ although the information must be available somewhere. Otherwise, how could the program call the function? However, GCC provides

When exactly does the compiler create a virtual function table? 1) when the class contains at least one virtual function. OR 2) when the immediate base class contains at least one virtual function. OR 3) when any parent class at any level of the hierarchy contains at least one virtual function. A related question to this: Is it possible to give up dynamic dispatch in a C++ hierarchy? e.g. consider the following example. #include <iostream> using namespace std; class A { public: virtual void f(); }; class B: public A { public: void f(); }; class C: public B { public: void f(); }; Which classes

I was recently asked in an interview about object layout with virtual functions and multiple inheritance involved. I explained it in context of how it is implemented without multiple inheritance involved (i.e. how the compiler generated the virtual table, insert a secret pointer to the virtual table in each object and so on). It seemed to me that there was something missing in my explanation. So here are questions (see example below) What is the exact memory layout of the object of class C. Virtual tables entries for class C. Sizes (as returned by sizeof) of object of classes A, B and C. (8, 8

First of all, I want to make myself clear that I do understand that there is no notion of vtables and vptrs in the C++ standard . However I think that virtually all implementations implement the virtual dispatch mechanism in pretty much the same way (correct me if I am wrong, but this isn't the main question). Also, I believe I know how virtual functions work , that is, I can always tell which function will be called, I just need the implementation details. Suppose someone asked me the following: "You have base class B with virtual functions v1, v2, v3 and derived class D:B which overrides

Recently ran across a C++ linker error that was new to me. libfoo.so: undefined reference to `VTT for Foo' libfoo.so: undefined reference to `vtable for Foo' I recognized the error and fixed my problem, but I still have a nagging question: what exactly is a VTT? Aside: For those interested, the problem occurs when you forget to define the first virtual function declared in a class. The vtable goes into the compilation unit of the class's first virtual function. If you forget to define that function, you get a linker error that it can't find the vtable rather than the much more developer