智能指標的向下轉型

// BoostTest.cpp : 定義控制台應用程式的進入點。//#include "stdafx.h"#include <iostream>#include "boost/cast.hpp"#include "boost/shared_ptr.hpp"using namespace boost;using namespace std;class base1{public:virtual void print(){cout<<"base1::print"<<endl;}};class base2{public:void only_base2(){cout<<"only_base2()"<<endl;}};class derived : public base1, public base2{public:void print(){cout<<"derived::print"<<endl;}void only_here(){cout<<"derived::only_here()"<<endl;}void only_base2(){cout<<"oops, here too!"<<endl;}};int main() {shared_ptr<base1> p(new derived);p->print();try{shared_ptr<derived> pD(shared_polymorphic_cast<derived>(p));pD->only_here();pD->only_base2();shared_ptr<base2> pB(shared_polymorphic_cast<base2>(p));pB->only_base2();}catch(bad_cast &e){cout<<e.what()<<endl;}}