C++程序设计(第2版)课后习题答案第14章

14.5

/*
author:shajin
date:2013-4-6
*/
#include <iostream>
#include<math.h>
using namespace std;
class Shape
{
public:
    double area();
    double girth();
    void show();
};
double Shape::area()
{
    return 0;
}

double Shape::girth()
{
    return 0.0;
}

void Shape::show()
{
    cout<<"Shape Object:"<<endl;
}

class Circle:public Shape
{
private:
    double radius;
public:
    Circle(double radius=5.0);
    double area();
    double girth();
    void show();
};


Circle::Circle(double r)
{
    radius=r;
}

double Circle::area()
{
    return 3.14*radius*radius;
}

void Circle::show()
{
    cout<<"Circle:"<<radius<<endl;
    cout<<"面积"<<area()<<endl;
    cout<<"周长"<<girth()<<endl;
}

double Circle::girth()
{
    return 2*3.14*radius;
}

class Triangle:public Shape
{
private:
    double a,b,c;//三角形三边
public:
    Triangle(double a=3.0,double b=4.0,double c=5.0);
    //需要判断是否能构成三角形
    double area();
    double girth();
    void show();
};
Triangle::Triangle(double a,double b,double c)
{
    this->a=a;
    this->b=b;
    this->c=c;
}
double Triangle::area()
{
    double s=(a+b+c)/2;
    return sqrt(s*(s-a)*(s-b)*(s-c));
}
double Triangle::girth()
{
    return a+b+c;
}
void Triangle::show()
{
    cout<<"Triangle:"<<a<<b<<c<<endl;
    cout<<"面积"<<area()<<endl;
    cout<<"周长"<<girth()<<endl;
}


class Rectangle:public Shape
{
private:
    double width,height;
public:
    Rectangle(double w=1.0,double h=1.0);
    double area();
    double girth();
    void show();
};
Rectangle::Rectangle(double w,double h)
{
    width=w;
    height=h;
}
double Rectangle::area()
{
    return width*height;
}
double Rectangle::girth()
{
    return 2*(width+height);
}
void Rectangle::show()
{
    cout<<"Rectangle:"<<width<<height<<endl;
    cout<<"面积"<<area()<<endl;
    cout<<"周长"<<girth()<<endl;
}
void main()
{
    Circle c(1);
    c.show();

    Triangle t;
    t.show();

    Rectangle r(3,4);
    r.show();
}

14.6

// 文件point.h: 类Point的定义
#if !defined __POINT__H__
#define __POINT__H__

#include <iostream.h>

class Point
{
    friend ostream &operator << (ostream &, const Point &);
public:
    // 重载的构造函数
    Point(double = 0, double = 0);
    Point(const Point &p); // 复制构造函数

    // 析构函数
    ~Point();

    // 重载的定值函数
    void setPoint(double a, double b);
    void setPoint(Point &p);

    // 取值函数
    double getX()const
    {
        return x;
    } double getY()const
    {
        return y;
    }

private:
    double x, y;
};

#endif

// 文件point.cpp: 类Point的实现
#include "point.h"

Point::Point(double a, double b)
{
    x = a;
    y = b;
}

Point::Point(const Point &p)
{
    x = p.getX();
    y = p.getY();
}

Point::~Point(){}

void Point::setPoint(double a, double b)
{
    x = a;
    y = b;
}

void Point::setPoint(Point &p)
{
    x = p.getX();
    y = p.getY();
}

ostream &operator << (ostream &os, const Point &point)
{
    os << "(" << point.x << ", " << point.y << ")";
    return os;
}

// 文件line.h: 类Line的定义
#if !defined __LINE__H__
#define __LINE__H__

#include <iostream.h>
#include "point.h"

class Line {
    friend ostream & operator<< (ostream &, const Line &);
public:
    // 重载的构造函数
    Line(double startX = 0, double startY = 0, double endX = 0, double endY = 0);
    Line(Point start, Point end);
    Line(Line &line);    //复制构造函数

    // 析构函数
    ~Line();

    // 重载的定值函数
    void setLine(double startX = 0, double startY = 0, double endX = 0, double endY = 0);
    void setLine(Point , Point );

    double getLength() const; // 计算线段的长度

    // 取值函数
    Point getStartPoint()  {return startPoint;}
    Point getEndPoint()  {return endPoint;}

private:
    Point startPoint, endPoint;
};

#endif