了解object slicing

#include <iostream>

using namespace std;

class Grandfather...{

public:

    virtual void display()=0;

    void run()...{                   

        cout<<"Grandfather Run!!! ";

    }

};

class Father:public Grandfather...{

public:

    int fatherValue;

    void display()...{

        cout<<"Father Display!! ";

    }

    void run()...{

        cout<<"Father Run!!! ";

    }

};

class Uncle:public Grandfather...{

public:

    int uncleValue;

    void display()...{

        cout<<"Uncle Display!! ";

    }

    void run()...{

        cout<<"Uncle Run!!! ";

    }

};

class Son:public Father...{

public:

    int sonValue;

    void display()...{

        cout<<"Son Display!! ";

    }

};

void main()...{

    Grandfather* grandfather_pt=NULL;

    Father* father_pt=NULL;

    Son* son_pt=NULL;

    Father father;

    Uncle uncle;

    Son son;

    cout<<"靜态綁定 不用virtual關鍵字： ";

    grandfather_pt=&uncle;

    grandfather_pt->run();

    grandfather_pt=&father;

    grandfather_pt->run();

    cout<<" 動态綁定 純虛函數： ";

    grandfather_pt=&uncle;

    grandfather_pt->display();

    grandfather_pt=&father;

    grandfather_pt->display();

    cout<<" 指針強制轉換 ";

    ( (Father*)(&son) )->display();

//    ( (Father*)(&son) )->run();

    cout<<" 對象強制轉換 ";

    ((Father)son).display();        //隻允許upcasting，不允許downcasting

    cout<<" 編譯器為了防止對象切割的發生，自動調用拷貝構造函數，是以，比較位址： ";

    cout<<( father_pt=&((Father)son) )<<endl;    //注意優先級

    cout<<&son<<endl;

    cout<<"發現二者不同！ ";

}

 輸出為：

靜态綁定 不用virtual關鍵字：

Grandfather Run!!!

Grandfather Run!!!

 動态綁定 純虛函數：

Uncle Display!!

Father Display!!

 指針強制轉換

Son Display!!

 對象強制轉換 Father Display!!

 編譯器為了防止對象切割的發生，自動調用拷貝構造函數，是以，比較位址：

//0012FDB8

//0012FE88

發現二者不同！

本文來自CSDN部落格，轉載請标明出處：http://blog.csdn.net/SearchLife/archive/2009/03/12/3985139.aspx