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(3, 4, 5, 6);
    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(3, 4);
    Rectangle r1(3, 4, 5, 6);
    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(1, 2);//基类对象a
    Rectangle b(3, 4, 5, 6);//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(53);
    obj.showA();//输出a=53
    obj.setC(55, 58);
    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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