周二（作业节选）

#include<iostream>
using namespace std;
class CPolygon{
protected:
int width,height;
public:
void set_values(int a,int b)
{width=a;height=b;}
};
class CRectangle:public CPolygon{
public:
int area()
{return(width*height);}
};

class CTriangle:public CPolygon{
public:
int area()
{return(width*height/2);}
};
int main(){
CRectangle rect;
CTriangle trgl;
rect.set_values(4,5);
trgl.set_values(4,5);
cout<<rect.area()<<endl;
cout<<trgl.area()<<endl;
return 0;
}

//Complex.h
#pragma once
#include<iostream>
using namespace std;
class Complex
{
public:
Complex(double real=0.0,double image=0.0)
{this->real=real,this->image=image;
}
~Complex(void);
void display();
Complex operator+(Complex B);
private:
    double real;
    double image;
};

//Complex.cpp
#include"Complex.h"
Complex::~Complex(void){}
void Complex::display(){
cout<<real;
if(image>0)
cout<<"+";
cout<<image<<"i";
}
Complex Complex::operator+(Complex B){
return Complex(this->real+B.real,this->image+B.image);
}


//main.cpp
#include"Complex.h"
void main()
{
Complex A(1.0,2.0),B(3.0,4.0),C;
cout<<"Complex A:";
A.display();
cout<<endl;
cout<<"Complex B:";
B.display();
cout<<endl;
C=A+B;
cout<<"Complex A+B:";
C.display();
cout<<endl;
}