基類TableTennisPlayer  派生類RatedPlayer

1.       基類指標可以在不進行顯示型別轉換的情況下指向派生類物件;基類引用可以在不進行顯示型別轉換的情況下引用派生類物件.

RatedPlayer palyer(1000,”Mallory”,true)  

TableTennisPlayer &rt = palyer;

TableTennisPlayer *pt = palyer;

2.       不可以將基類物件和地址賦給派生類引用和指標

TableTennisPlayer palyer(1000,“Betsy”);

RatedPlayer&rt = palyer;  ///NOT ALLOWED

RatedPlayer*pt = palyer;  ///NOT ALLOWED

3.       如果沒有使用virtual,將根據引用型別或指標型別選擇方法,如果使用了virtual,將根據引用或指標指向的物件來選擇方法.

class Brass

{

private:

       string m_name;

       intm_age;

public:;

    Brass(conststring name,int age):m_name(name),m_age(age){};

       virtual void study(){cout<<"jackis studying C++"

       voidlove(){cout<<"Brass love"<<endl;}

};

class BrassPluse:publicBrass

{

private:

       string m_company;

public:

       BrassPluse(conststring &name,int age,const string &company):Brass(name,age),m_company(company){};

       virtual void study(){cout<<"jackis studying C++ in Tencent "

       voidlove(){cout<<"BrassPluse love"<<endl;}

};

void main()

{

       Brass dom("jack",24);

       BrassPluse doc("jack",24,"Tencent");

       Brass & rt =dom;

       Brass & rc =doc;

///定義virtual

       rt.study();

       rc.study();

       ///沒有定義virtual

       rt.love();

       rc.love();

       system("pause");

}