vtable

问题 This question already has answers here : Qt Linker Error: “undefined reference to vtable” [duplicate] (9 answers) Closed 4 years ago . I am working on a program in Qt using c++. But i got stuck at this point because of this error. The weird thing is that i created a separate program in which the following code worked but when i put the code inside my program i get an error. error: undefined reference to `vtable for Create_button_config' The error is in the Header file in which i create the

问题 This question already has answers here : Qt Linker Error: “undefined reference to vtable” [duplicate] (9 answers) Closed 4 years ago . I am working on a program in Qt using c++. But i got stuck at this point because of this error. The weird thing is that i created a separate program in which the following code worked but when i put the code inside my program i get an error. error: undefined reference to `vtable for Create_button_config' The error is in the Header file in which i create the

问题 Virtual function calls can be slow due to virtual calls requiring an extra indexed deference to the v-table, which can result in a data cache miss as well as an instruction cache miss... Not good for performance critical applications. So I have been thinking of a way to overcome this performance issue of virtual functions yet still having some of the same functionality that virtual functions provide. I am confident that this has been done before, but I devised a simple test that allows the

问题 Virtual function calls can be slow due to virtual calls requiring an extra indexed deference to the v-table, which can result in a data cache miss as well as an instruction cache miss... Not good for performance critical applications. So I have been thinking of a way to overcome this performance issue of virtual functions yet still having some of the same functionality that virtual functions provide. I am confident that this has been done before, but I devised a simple test that allows the

问题 Supressing C++ vtable generation can be done in MSVC using the __declspec(novtable) attribute. However, it seems that there is no equivalent attribute for the GNU C++ compiler. The fact is that leaving the vtables for pure virtual classes unnecessarily links in __cxa_abort() and many others, and I want to avoid this happening because I'm programming for an embedded system. So, what should I do? struct ISomeInterface { virtual void Func() = 0; }; class CSomeClass : public ISomeInterface {

问题 Trying to make a Fraps type program. See comment for where it fails. #include "precompiled.h" typedef IDirect3D9* (STDMETHODCALLTYPE* Direct3DCreate9_t)(UINT SDKVersion); Direct3DCreate9_t RealDirect3DCreate9 = NULL; typedef HRESULT (STDMETHODCALLTYPE* CreateDevice_t)(UINT Adapter, D3DDEVTYPE DeviceType, HWND hFocusWindow, DWORD BehaviorFlags, D3DPRESENT_PARAMETERS* pPresentationParameters, IDirect3DDevice9** ppReturnedDeviceInterface); CreateDevice_t RealD3D9CreateDevice = NULL; HRESULT

问题 gsoap with its tools wsdl2h and soapcpp2 provided me with a soapStub.h file containing the following: class SOAP_CMAC ns2__SOAPKunden { public: std::string *adresszusatz; // ... public: virtual int soap_type() const { return 7; } // ... ns2__SOAPKunden() : adresszusatz(NULL), x(NULL) { } // left out all member init. virtual ~ns2__SOAPKunden() { } }; I start with a small app using the class to populate objects with data from informix DB. But to compile successfully i have to leave away all the

问题 I am trying to write an Http proxy that basically works like indianwebproxy So i fired up qtcreator and but one of my classes is failing to compile with the infamous error : undefined reference to vtable for HttpProxyThreadBrowser . I can't figure out why its doing this. I read through similar questions on Stackoverflow and apparently the problem is with undefined virtual methods that are not pure But i have not declared any virtual functions. Here is my class class HttpProxyThreadBrowser :

问题 I read a lot of people writing "a virtual table exists for a class that has a virtual function declared in it". My question is, does a vtable exists only for a class that has a virtual function or does it also exist for classes derived from that class. e.g class Base{ public: virtual void print(){cout<<"Base Print\n";} }; class Derived:public Base{ public: void print(){cout<<"Derived print\n";} }; //From main.cpp Base* b = new Derived; b->print(); Question: Had there been no vtable for class

问题 this is kind of homework question. For the following code, #include <iostream> using namespace std; class A { public: virtual void f(){} }; class B { public: virtual void f2(){} }; class C: public A, public B { public: virtual void f3(){} }; class D: public C { public: virtual void f4(){} }; int main() { cout<<sizeof(D)<<endl; } The output is: 8 Could anyone please explain how it is 8 bytes? If the vtable implementation is compiler dependent, what should I answer for this kind of question in