由于每个对象都需要对应其所属类型的vtbl,以便在通过指针或引用调用虚函数时实现动态绑定,这就导致了虚函数的第二个成本:每个对象都内含一vptr,用于指向该类的vtbl. vptr被加入对象的某个位置,不同编译器对此实现不同,如果vptr加入到对象尾端(以下都假设vptr加入到尾端),那么对象构造看起来像这样: 4字节的vptr导致...
override of virtual function "Person::VDescribe" is ambiguous 'PartTimeStudent': ambiguous inheritance of 'void Person::VDescrive(void)' 'PartTimeStudent': ambiguous inheritance of 'void Person::VDescribe(void)' Run Code Online (Sandbox Code Playgroud) 但是,仅当Student和Employee都实现VDescribe...
条款24:了解 virtual functions、multiple inheritance、virtual base classes、runtime type identification的成本书名: More Effective C++:35个改善编程与设计的有效方法(中文版)作者名: (美)斯考特·梅耶本章字数: 5035字更新时间: 2020-09-05 00:28:41
编译器会为每个存在虚函数的类对象插入一个vtpr(virtul function pointer)，该vptr指向存放了虚函数地址...
The most obvious problem with multiple inheritance occurs during function overriding. Suppose two base classes have the same function which is not overridden in the derived class. If you try to call the function using the object of the derived class, the compiler shows error. It's because the...
// The non virtual function move() is inherited but cannot be overridden void eat(void) { std::cout << "Llamas eat grass!" << std::endl; } }; This allows a programmer to process a list of objects of class Animal, telling each in turn to eat (by calling eat()), without needing...
struct Class{ virtual void f() = 0 ; int i ; }; int foo( Class& c ) { c.f() ; /* mov rax, QWORD PTR [rdi] // get the vtbl pointer in the object (into rax) call [QWORD PTR [rax]] // look up the vtbl and call the function */ } https://gcc.godbolt.org/z/fo4K...
does not introduce an overrider, C::f is final in E{usingA::f;// not a function declaration, just makes A::f visible to lookup};intmain(){E e;e.f();// virtual call calls C::f, the final overrider in ee.E::f();// non-virtual call calls A::f, which is visible in E}...
Because of virtual inheritance, when the write() function from the transmitter class is called, the method read() from the receiver class gets called (as you may have noticed, the transmitter class doesn't have a read() function). In the above hierarchy we can instantiate only the radio ...
On a personal note, I'm atOculus VRand it is amazing - fabulous people doing fabulous work. We're hiring more fabulous people sowrite meif that's you! Section:Inheritance — multiple and virtual inheritance←(in the new Super-FAQ) ...