04737_C++程序设计_第6章_继承和派生

例6.1

使用默认内联函数实现单一继承。

 #include<iostream>

 using namespace std;

 class Point
 {
 private:
     int x, y;
 public:
     Point(int a, int b)
     {
         x = a;
         y = b;
         cout << "Point..." << endl;
     }
     void Showxy()
     {
         cout << "x=" << x << "y=" << y << endl;
     }
     ~Point()
     {
         cout << "Delete Point" << endl;
     }
 };

 class Rectangle :public Point
 {
 private:
     int H, W;
 public:
     Rectangle(int a, int b, int h, int w) :Point(a, b)//构造函数初始化列表
     {
         H = h;
         W = w;
         cout << "Rectangle..." << endl;
     }
     void Show()
     {
         cout << "H=" << H << ",W" << W << endl;
     }
     ~Rectangle()
     {
         cout << "Delete Rectangle" << endl;
     }
 };

 void main()
 {
     Rectangle r1(, , , );
     r1.Showxy();
     r1.Show();

     system("pause");
 }

例6.2

演示使用protected成员。

 #include <iostream>

 using namespace std;

 class Point
 {
 protected:
     int x, y;//声明保护数据成员
 public:
     Point(int a, int b)
     {
         x = a;
         y = b;
     }
     void Show()
     {
         cout << "x=" << x << ",y=" << y << endl;//基类的Show()函数
     }
 };

 class Rectangle :public Point
 {
 private:
     int H, W;
 public:
     Rectangle(int, int, int, int);//构造函数原型
     void Show()
     {
         cout << "x=" << x << ",y=" << y << ",H=" << H << ",W=" << W << endl;
     }
 };

 Rectangle::Rectangle(int a, int b, int h, int w) :Point(a, b)//定义构造函数
 {
     H = h;
     W = w;
 }

 void main()
 {
     Point a(, );
     Rectangle r1(, , , );
     a.Show();//基类对象调用基类Show()函数
     r1.Show();//派生类对象调用派生类Show()函数

     system("pause");
 }

例6.3

使用Point和Rectangle类演示赋值兼容规则的例子。

 #include <iostream>

 using namespace std;

 class Point
 {
 protected:
     int x, y;//声明保护数据成员
 public:
     Point(int a, int b)
     {
         x = a;
         y = b;
     }
     void Show()
     {
         cout << "x=" << x << ",y=" << y << endl;//基类的Show()函数
     }
 };

 class Rectangle :public Point
 {
 private:
     int H, W;
 public:
     Rectangle(int, int, int, int);//构造函数原型
     void Show()
     {
         cout << "x=" << x << ",y=" << y << ",H=" << H << ",W=" << W << endl;
     }
 };

 Rectangle::Rectangle(int a, int b, int h, int w) :Point(a, b)//定义构造函数
 {
     H = h;
     W = w;
 }

 void main()//演示公有继承的赋值兼容性规则
 {
     Point a(, );//基类对象a
     Rectangle b(, , , );//派生类对象b
     a.Show();
     b.Show();

     Point& ra = b;//派生类对象初始化基类的引用
     ra.Show();//实际调用的是基类的Show函数

     Point *p = &b;//派生类对象的地址赋给指向基类的指针
     p->Show();//实际调用的是基类的Show函数

     Rectangle *pb = &b;//派生类指针pb
     pb->Show();//调用派生类的Show函数

     a = b;//派生类对象的属性值更新基类对象的属性值
     a.Show();

     system("pause");
 }

例6.5

演示多重继承的例子。

 #include <iostream>

 using namespace std;

 class A
 {
 private:
     int a;
 public:
     void setA(int x)
     {
         a = x;
     }
     void showA()
     {
         cout << "a=" << a << endl;
     }
 };

 class B
 {
 private:
     int b;
 public:
     void setB(int x)
     {
         b = x;
     }
     void showB()
     {
         cout << "b=" << b << endl;
     }
 };

 class C :public A, public B
 {
 private:
     int c;
 public:
     void setC(int x, int y)
     {
         c = x;
         setB(y);
     }
     void showC()
     {
         showB();
         cout << "c=" << c << endl;
     }
 };

 void main()
 {
     C obj;

     obj.setA();
     obj.showA();//输出a=53
     obj.setC(, );
     obj.showC();//输出b=58 c=55

     system("pause");
 }

例6.6

访问具有二义性的例子。

 #include <iostream>

 using namespace std;

 class A
 {
 public:
     void func()
     {
         cout << "a.func" << endl;
     }
 };

 class B
 {
 public:
     void func()
     {
         cout << "b.func" << endl;
     }
     void gunc()
     {
         cout << "b.gunc" << endl;
     }
 };

 class C :public A, public B
 {
 public:
     void gunc()
     {
         cout << "c.gunc" << endl;
     }
     void hun1()
     {
         A::func();
     }
     void hun2()
     {
         B::func();
     }
 };

 void main()
 {
     C obj;

     obj.A::func();//输出a.func
     obj.B::func();//输出b.func
     obj.B::gunc();//输出b.func
     obj.C::gunc();//输出c.gunc

     obj.gunc();//输出c.gunc
     obj.hun1();//输出a.func
     obj.hun2();//输出b.func

     system("pause");
 }

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