C++中可以使用虚函数的概念，实现动态绑定，C语言没有 C++中的虚函数（Virtual function）是一种用于实现运行时多态（Runtime Polymorphism）的关键技术，它允许在基类中声明一个函数为虚函数，并且在派生类中重写该虚函数。当通过基类的指针或引用调用虚函数时，程序会根据实际对象类型来动态地绑定相应的函数实现，从而...
class Virtualbase { public: virtual void Demon()= 0; //pure virtual function virtual void Base() { cout<<"This is farther class.\n"; } }; //sub class class SubVirtual :public Virtualbase { public: void Demon() { cout<<"This is SubVirtual!\n"; ...
classPoint { private: intx,y; public: Point(intx=0,inty=0) { this->x = x; this->y = y; } virtualdoublearea() { return0.0; } }; classCircle:publicPoint { private: intr; public: Circle(intx,inty,intR):Point(x,y) { r = R; } doublearea() { returnPI*r*r; } }; intm...
我们已经知道,虚(virtual)函数的一般实现模型是:每一个类(class)有一个虚表(virtual table),内含该class之中有作用的虚(virtual)函数的地址,然后每个对象有一个vptr,指向虚表(virtual table)的所在。 每一个类有一个虚表,每一个类的对象有一个指向虚表的指针vptr 请允许我援引自深度探索c++对象模型一书上的一个...
class CV2{ virtual void a(){} virtual void b(){} int c; }; int main() { int nsize1 = sizeof(CV1); int nsize2 = sizeof(CV2); return 0; } 看一下反汇编代码: ok提到了虚函数表,下面我们来看一下虚函数表: 对C++了解的人都应该知道虚函数(Virtual Function)是通过一张虚函数表(Vir...
function to be an overrider but it is (because it happens to have the same signature as a virtual in the base class -- note this problem arises whether or not the function is explicitly declared virtual, because the programmer may have intended to create either a new virtual function or a...
virtual void VFun2() { printf(__FUNCTION__ "\n"); } virtual ~CBase() { printf(__FUNCTION__ "\n"); } int data; }; class CDerived : public CBase { public: virtual void VFunNew() { printf(__FUNCTION__ "\n"); } virtual void VFun1() override { printf(__FUNCTION__ "\n...
function to be an overrider but it is (because it happens to have the same signature as a virtual in the base class -- note this problem arises whether or not the function is explicitly declared virtual, because the programmer may have intended to create either a new virtual function or a...
virtual [type-specifiers] member-function-declarator virtual [access-specifier] base-class-name Parameters type-specifiers Specifies the return type of the virtual member function. member-function-declarator Declares a member function. access-specifier ...
这里的数组就是虚函数表(Virtual function table),简写为vtable。 我们以下面的继承关系为例进行讲解: #include <iostream> #include <string> using namespace std; //People类*** class People{ public: People(string name, int age); public: virtual void display(); virtual void eating(); protected: ...