C++中的RTTI(runtime type information) 机制

#include <iostream>#include <typeinfo>using namespace std;class Shape {public:virtual void Print()=0;};class Circle:public Shape {public:virtual void Print() override {cout << "this is a Circle" << endl;}};class Square:public Shape {public:virtual void Print() override {cout << "this is a Square" << endl;}};int main() {Shape *s[2];s[0] = new Circle;s[1] = new Square;for(int i=0;i<2; i++) {//1.运行时转型，必须含有虚函数virtual,安全向下转型//RTTI(runtime type information)if(dynamic_cast<Circle*>(s[i])) {cout << "hello Circle" << endl;s[i]->Print();}if(dynamic_cast<Square*>(s[i])) {cout << "hello Square" << endl;s[i]->Print();}}cout << typeid(*s[0]).name() << endl; //typeid是运行时期的事情，也就是动态类型cout << typeid(Circle).name() << endl;if(typeid(Circle).name() == typeid(*s[0]).name()) {cout << "p is point to a Circle object" << endl;((Circle*)s[0])->Print();}//type_info ti = typeid(Circle);  //privatereturn 0;}/*class type_info{public:    virtual ~type_info();    bool operator==(const type_info& _Rhs) const; // 用于比较两个对象的类型是否相等    bool operator!=(const type_info& _Rhs) const; // 用于比较两个对象的类型是否不相等    bool before(const type_info& _Rhs) const;    // 返回对象的类型名字，这个函数用的很多    const char* name(__type_info_node* __ptype_info_node = &__type_info_root_node) const;    const char* raw_name() const;private:    void *_M_data;    char _M_d_name[1];    type_info(const type_info& _Rhs);    type_info& operator=(const type_info& _Rhs);    static const char * _Name_base(const type_info *,__type_info_node* __ptype_info_node);    static void _Type_info_dtor(type_info *);};*/