C++里的继承和多态（中）——分析单继承、多继承、菱形继承（不含虚函数）

来源：互联网发布：java基础知识点汇总编辑：程序博客网时间：2024/05/17 03:22

1、单继承

class Base{public:                Base()                {                                cout << "Base()" << this << endl;                }                 void FunTest1()                {                                cout << "Base::FunTest1()" << endl;                }                 void FunTest2()                {                                cout << "Base::FunTest2()" << endl;                }                ~Base()                {                                cout << "~Base()" << endl;                }                 int _data1;};class Derive :public Base{public:                 void FunTest3()                {                                cout << "Derive::FunTest3()" << endl;                }                 int _data2;};int main(){                 Base b;                b.FunTest1();                b.FunTest2();                b._data1 = 0x04;                 Derive d;                d.FunTest1();                d.FunTest2();                d.FunTest3();                d._data1 = 0x01;                d._data2 = 0x02;                 return 0;}

——b对象和d对象的对象模型

main 函数的反汇编

派生类的构造函数：

程序运行结果：

构造函数：

基类构造函数：Base( )884 ->派生类构造函数： Base( )874 ->Derive( )874

析构函数：

派生类的析构函数：~Derive( )874 -> ~Base( )874->基类的析构函数：~Base( )884

2、多继承

class Base{public:                Base()                {                                cout << "Base()" << this << endl;                }                 void FunTest1()                {                                cout << "Base::FunTest1()" << endl;                }                 void FunTest2()                {                                cout << "Base::FunTest2()" << endl;                }                ~Base()                {                                cout << "~Base()" << endl;                }                 int _data1;};class Base1{public:                Base1()                {                                cout << "Base1()" << endl;                }                 void FunTest3()                {                                cout << "Base::FunTest3()" << endl;                }                 void FunTest4()                {                                cout << "Base::FunTest4()" << endl;                }                 int _data3;};class Derive :public Base,public Base1{public:                Derive()                {                                cout << "Derive()" << this << endl;                }                 void FunTest5()                {                                cout << "Derive:FunTest5()" << endl;                }                ~Derive()                {                                cout << "~Derive()" << endl;                }                 int _data2;};int main(){                 Base b;                b.FunTest1();                b.FunTest2();                b._data1 = 0x04;                 Base1 b1;                b1.FunTest3();                b1.FunTest4();                b1._data3 = 0x05;                 Derive d;                d.FunTest1();                d.FunTest2();                d.FunTest3();                d.FunTest4();                d.FunTest5();                d._data1 = 0x01;                d._data2 = 0x02;                d._data3 = 0x03;                 return 0;}

对象模型：

main函数的反汇编：

派生类的构造函数：

先调用Base的构造函数，再调用Base1的构造函数

析构函数的调用：

先是派生类的析构函数，再试Base1的析构函数，最后是Base的析构函数

在派生类的析构函数中又会调用基类的析构函数：

在派生类的析构函数中，也是先调用Base1的析构函数，再调用Base的析构函数。与构造函数的顺序正好相反

程序运行的结果：

构造函数：

j基类的构造函数：Base( )D9c -> Base1( )D90 -> 派生类中的构造函数：Base( )D7c -> Base1 ( )D80 -> Derive( )D7c

析构函数：

派生类中的析构函数：~Derive( )D7c -> ~Base1( )D80 -> ~Base( )D7c ->基类的析构函数：~Base1( )D90 -> ~Base( )D9C

3、菱形继承

class Base{public :                Base()                {                                cout << "Base()" << this << endl;                }                 void FunTest1()                {                                cout << "Base::FunTest1()" << endl;                }                ~Base()                {                                cout << "~Base()" << endl;                }};class Derive : public Base{public :                Derive()                {                                cout << "Derive()" << this << endl;                }                 void FunTest2()                {                                cout << "Derive:FunTest2()" << endl;                }                ~Derive()                {                                cout << "~Derive()" << endl;                }};class Derive1 : public Base{public :                Derive1()                {                                cout << "Derive1()" << this << endl;                }                 void FunTest3()                {                                cout << "Derive:FunTest4()" << endl;                }                ~Derive1()                {                                cout << "~Derive1()" << endl;                }};class Derive2 : public Derive ,public Derive1{public :                Derive2()                {                                cout << "Derive2()" << endl;                }                 void FunTest4()                {                                cout << "Derive:FunTest4()" << endl;                }};int main(){                 Base b;                b.FunTest1();                 Derive d;                d.FunTest1();                d.FunTest2();                 Derive1 d1;                d1.FunTest1();                d1.FunTest3();                 Derive2 d2;                 //d2.FunTest1();会出现二义性                d2. Derive ::FunTest1();                d2. Derive1 ::FunTest1();                d2.FunTest2();                d2.FunTest3();                d2.FunTest4();                 return 0;}

对象模型：

Derive和Derive1中都含有了Base，会产生二义性和数据冗余。