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）

  继承

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;
}

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。

main函数的反汇编：

派生类的构造函数：

在派生类的构造函数中，都先调用的基类的构造函数。

Derive（）

Derive1（）

Derive2（）

析构函数的调用：

析构函数的顺序和构造函数的顺序正好相反。

~Derive2( )->~Derive1( )->~Derive( )->~Base( )，

派生类中析构函数的调用：

在~Derive2（），先是自己的析构函数，再调用了~Derive1（），再调用了~Derive（），

在~Derive1( )中先是自己的析构函数，又调用了~Base（）

在~Derive( )中先是自己的析构函数，又调用了~Base（）

程序运行结果：

构造函数：

Base( )B8F   ->

Derive的构造函数：Base( )B83 -> Derive( )B83->

Derive1的构造函数：Base( )B77 -> Derive1( )B77->

Derive2的构造函数：Base( )B6B -> Derive( )B6B     ->Base( )B6C -> Derive1( )B6C         ->Derive2( )B6B

析构函数：

~Derive2( )B6B -> ~Derive1( )B6C ->~Base( )B6C -> ~Derive( )B6B -> ~Base( )B6B 

~Derive1( )B77 -> ~Base( )B77 -> ~Derive( )B83 -> ~Base( )B83 

~Base( )B8F