C++面向对象程序的设计第六章课后习题答案(第2版—谭浩强).docx

第六章课后习题答案〔第二版谭浩强〕
1:
//xt6-1/cpp
#include //如用VC++应改为∶#include
using namespace std; //如用VC++应取消此行
#include "cylinder.h"
#include "point.cpp"
#include "circle.cpp"
#include "cylinder.cpp"
int main()
{Cylinder cy1(3.5,6.4,5.2,10);
cout<<"\noriginal cylinder:\nx="<
Circle &cRef=cy1;
cout<<"\ncRef as a Circle:"<
using namespace std;
class Point

{public:
Point(float a,float b):x(a),y(b){}
~Point(){cout<<"executing Point destructor"<lic Point
{public:
Circle(float a,float b,float r):Point(a,b),radius(r){}
~Circle(){cout<<"executing Circle destructor"<
using namespace std;
class Point
{public:
Point(float a,float b):x(a),y(b){}
~Point(){cout<<"executing Point destructor"<ate:
float radius;
};

int main()
{Point *p=new Circle(2.5,1.8,4.5);
Circle *pt=new Circle(2.5,1.8,4.5);
delete pt;
return 0;
}
3：解法三
#include
using namespace std;
class Point
{public:
Point(float a,float b):x(a),y(b){}
virtual ~Point(){cout<<"executing Point destructor"<lete p;
}
4：
#include
using namespace std;
//定义抽象基类Shape
class Shape
{public:
virtual double area() const =0; //纯虚函数
};

//定义Circle类
class Circle:public Shape
{public:
Circle(double r):radius(r){} //结构函数
virtual double area() const {return 3.14159*radius*radius;}; //定义虚函数
protected:
double radius; //半径
};

//定义Rectangle类
class Rectangle:public Shape
{public:
Rectangle(double w,double h):width(w),height(h){} //结构函数
virtual double area() const {return width*height;} //定义虚函数
protected:
double width,height; //宽与高
};

class Triangle:public Shape
{public:
Triangle(double w,double h):width(w),height(h){} //结构函数
virtual double area() const {return 0.5*width*height;} //定义虚函数
protected:
double width,height; //宽与高
};

//输出面积的函数
void printArea(const Shape &s)
{cout< //建立Circle类对象circle
cout<<"area of circle =";
printArea(circle); //输出circle的面积
Rectangle rectangle(4.5,8.4); //建立Rectangle类对象rectangle
cout<<"area of rectangle =";
printArea(rectangle); //输出rectangle的面积
Triangle triangle(4.5,8.4); //建立Triangle类对象
cout<<"area of triangle =";
printArea(triangle); //输出triangle的面积
return 0;
}
5：
#include
using namespace std;
//定义抽象基类Shape
class Shape
{public:
virtual double area() const =0; //纯虚函数
};

//定义Circle(圆形)类
class Circle:public Shape
{public:
Circle(double r):radius(r){} //结构函数
virtual double area() const {return 3.14159*radius*radius;}; //定义虚函数
protected:
double radius; //半径
};

//定义Square(正方形)类
class Square:public Shape
{public:
Square(double s):side(s){} //结构函数
virtual double area() const {return side*side;} //定义虚函数
protected:
double side;
};
//定义Rectangle(矩形)类
class Rectangle:public Shape
{public:
Rectangle(double w,double h):width(w),height(h){} //结构函数
virtual double area() const {return width*height;} //定义虚函数
protected:
double width,height; //宽与高
};

//定义Trapezoid(梯形)类
class Trapezoid:public Shape
{public:
Trapezoid(double t,double b,double h):top(t),bottom(t),height(h){} //结构函数
virtual double area() const {return 0.5*(top+bottom)*height;} //定义虚函数
protected:
double top,bottom,height; //上底、下底与高
};

//定义Triangle(三角形)类
class Triangle:public Shape
{public:
Triangle(double w,double h):width(w),height(h){} //结构函数
virtual double area()const {return 0.5*width*height;} //定义虚函数
protected:
double width,height; //宽与高
};

int main()
{
Circle circle(12.6); //建立Circle类对象circle
Square square(3.5); //建立Square类对象square
Rectangle rectangle(4.5,8.4); //建立Rectangle类对象rectangle
Trapezoid trapezoid(2.0,4.5,3.2); //建立Trapezoid类对象trapezoid
Triangle triangle(4.5,8.4); //建立Triangle类对象
Shape *pt[5]={&circle,&square,&rectangle,&trapezoid,&triangle};
//定义基类指针数组pt，使它每一个元素指向一个派生类对象
double areas=0.0; //areas为总面积
for(int i=0;i<5;i++)
{areas=areas+pt[i]->area();}
cout<<"totol of all areas="<