实验三：多态性答案—专业版

1．定义一个复数类，通过重载运算符实现复数的四则运算、求负运算和赋值运算。

其中，要求加法“+”和减法“-”用友元函数实现重载，其他运算符用成员函数实现重载。

//main.cpp:#include "complex.h"int main(int argc , char *argv[]){COMPLEX c1,c2;cout<<"请输入第一个复数：\n";cin>>c1;cout<<"请输入第二个复数：\n";cin>>c2;cout<<"第一个复数是："<<c1<<endl;cout<<"第二个复数是："<<c2<<endl;cout<<"c1+c2的结果为："<<c1+c2<<endl;cout<<"c1-c2的结果为："<<c1-c2<<endl;cout<<"c1*c2的结果为："<<c1*c2<<endl;cout<<"c1/c2的结果为："<<c1/c2<<endl;cout<<"-c2的结果为："<<-c2<<endl;return 0;}// complex.h#include<iostream>using namespace std;class COMPLEX{protected:double real;double image;public:COMPLEX(double r=0, double i=0);COMPLEX(const COMPLEX& other);friend COMPLEX operator+(const COMPLEX& left,const COMPLEX& right);friend COMPLEX operator-(const COMPLEX& left,const COMPLEX& right);COMPLEX operator*(const COMPLEX& other);COMPLEX operator/(const COMPLEX& other);COMPLEX operator-();COMPLEX operator=(const COMPLEX& other);friend ostream& operator <<(ostream& stream, COMPLEX& obj);friend istream& operator >>(istream& stream, COMPLEX& obj); };COMPLEX::COMPLEX(double r, double i){real=r;image=i;}COMPLEX::COMPLEX(const COMPLEX& other){real=other.real;image=other.image;}COMPLEX COMPLEX::operator*(const COMPLEX& other){COMPLEX temp;temp.real=real*other.real-image*other.image;temp.image=real*other.image+other.real*image;return temp;}COMPLEX COMPLEX::operator/(const COMPLEX& other){COMPLEX temp;double v=other.real*other.real+other.image*other.image;if (v!=0.0){temp.real=(real*other.real+image*other.image)/v;temp.image=(image*other.real-real*other.image)/v;return temp;}cout<<"除法无效\n";return temp;}COMPLEX COMPLEX::operator-(){COMPLEX temp;temp.real=-real;temp.image=-image;return temp;}COMPLEX COMPLEX::operator=(const COMPLEX& other){real=other.real;image=other.image;return *this;}/////////////////////////////////////////////////////// 友元函数不是类的成员函数！！COMPLEX operator+(const COMPLEX& left, const COMPLEX& right) {COMPLEX temp;temp.real=left.real+right.real;temp.image=left.image+right.image;return temp;}COMPLEX operator-(const COMPLEX& left, const COMPLEX& right) {COMPLEX temp;temp.real=left.real-right.real;temp.image=left.image-right.image;return temp;}ostream& operator <<(ostream& stream, COMPLEX& obj){stream<<obj.real;if(obj.image>0) stream<<"+"<<obj.image<<"i";else if(obj.image<0) stream<<obj.image<<"i";return stream;}istream& operator >>(istream& stream, COMPLEX& obj){cout<<"输入实部：";stream>> obj.real;cout<<"输入虚部：";stream>> obj.image;return stream;}2．设计一个多态数组，该数组用于存放四种几何图形（三角形、矩形、正方形和圆），要求利用虚函数实现的多态性来求多态数组中几何图形的面积之和。

几何图形的类型可以通过构造函数或通过成员函数来设置。

//main.cpp#include "figure.h"int main(int argc, char* argv[]){FIGURE* pf[4];int i;double sum;TRIANGLE t(1,4,3,4);RECTANGLE r(3,4,5,6);SQUARE s(4,5,9);CIRCLE c(5,6,2);// 动态重载的要素：继承、指针pf[0]=&t;pf[1]=&r;pf[2]=&s;pf[3]=&c;// 求面积之和sum=0.0;for(i=0;i<4;i++){sum+=pf[i]->getArea();}cout<<"面积之和为: "<<sum<<endl;return 0;}//igure.h#include <iostream>using namespace std;const double PI=3.1415926;class FIGURE{public:FIGURE(double x, double y);virtual double getArea()=0;private:double x_pos;double y_pos;};class TRIANGLE:public FIGURE{public:TRIANGLE(double x, double y, double len, double hei);virtual double getArea();private:double length;double height;};class RECTANGLE:public FIGURE{public:RECTANGLE(double x, double y, double len, double wid);virtual double getArea();private:double length;double width;};class SQUARE:public FIGURE{public:SQUARE(double x, double y, double len);virtual double getArea();private:double length;};class CIRCLE:public FIGURE{public:CIRCLE(double x, double y, double r);virtual double getArea();private:double radius;};//////////////////////////////////////////////////////////////////////////////////// FIGURE::FIGURE(double x, double y)x_pos=x;y_pos=y;}TRIANGLE::TRIANGLE(double x, double y, double len, double hei):FIGURE(x,y) {length=len;height=hei;}double TRIANGLE::getArea(){return 0.5*length*height;}RECTANGLE::RECTANGLE(double x, double y, double len, double wid):FIGURE(x,y) {length=len;width=wid;}double RECTANGLE::getArea(){return length*width;}SQUARE::SQUARE(double x, double y, double len):FIGURE(x,y){length=len;}double SQUARE::getArea(){return length*length;}CIRCLE::CIRCLE(double x, double y, double r):FIGURE(x,y){radius=r;}double CIRCLE::getArea(){return PI*radius*radius;}。