第八周 项目一 实现复数类中的运算符重载（3）

问题及代码：

/*
*Copyright (c)2014,烟台大学计算机与控制工程学院
*All rights reserved.
*文件名称：Project.cpp
*作    者：chenqin.
*完成日期：2015年4月25日
*版 本 号：v1.0
*
*问题描述：定义一个定义完整的类（是可以当作独立的产品发布，成为众多项目中的“基础工程”）。这样的类在(2)的基础上，扩展+、-、*、/运算符的功能，使之能与double型数据进行运算。设Complex c; double d; c+d和d+c的结果为“将d视为实部为d的复数同c相加”，其他-、*、/运算符类似。
*程序输入：略
*程序输出：略
*/
#include <iostream>
using namespace std;
class Complex
{
public:
Complex()
{
real=0;
imag=0;
}
Complex(double r,double i)
{
real=r;
imag=i;
}
friend Complex operator+(const Complex &c1,Complex &c2);
friend Complex operator-(const Complex &c1,Complex &c2);
friend Complex operator*(const Complex &c1,Complex &c2);
friend Complex operator/(const Complex &c1,Complex &c2);
Complex operator+(double &i);
friend Complex operator+(double &i,Complex &c2);
Complex operator-(double &i);
friend Complex operator-(double &i,Complex &c2);
Complex operator*(double &i);
friend Complex operator*(double &i,Complex &c2);
Complex operator/(double &i);
friend Complex operator/(double &i,Complex &c2);
void display();
private:
double real;
double imag;
};
//下面定义成员函数
void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i)"<<endl;
}
Complex operator+(const Complex &c1,Complex &c2)
{

return Complex(c1.real+c2.real,c1.imag+c2.imag);
}
Complex Complex::operator+(double &i)
{
return Complex(real+i,imag);
}
Complex operator+(double &i,Complex &c2)
{
return Complex(i+c2.real,c2.imag);
}
Complex operator-(const Complex &c1,Complex &c2)
{
return Complex(c1.real-c2.real,c1.imag-c2.imag);
}
Complex Complex::operator-(double &i)
{
return Complex(real-i,imag);
}
Complex operator-(double &i,Complex &c2)
{
return Complex(i-c2.real,-c2.imag);
}
//复数相乘：(a+bi)(c+di)=(ac-bd)+(bc+ad)i.
Complex operator*(const Complex &c1,Complex &c2)
{
return Complex((c1.real*c2.real)-(c1.imag*c2.imag),(c1.imag*c2.real)+(c1.real*c2.imag));
}
Complex Complex::operator*(double &i)
{
return Complex(real*i,imag*i);
}
Complex operator*(double &i,Complex &c2)
{
return Complex(i*c2.real,i*c2.imag);
}
//复数相除：(a+bi)/(c+di)=(ac+bd)/(c^2+d^2) +(bc-ad)/(c^2+d^2)i
Complex operator/(const Complex &c1,Complex &c2)
{
return Complex((c1.real*c2.real+c1.imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag),(c1.imag*c2.real-c1.real*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag));
}
Complex Complex::operator/(double &i)
{
return Complex((real*i)/(i*i),(imag*i)/(i*i));
}
Complex operator/(double &i,Complex &c2)
{
return Complex((i*c2.real)/(c2.real*c2.real+c2.imag*c2.imag),(-i*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag));
}
//下面定义用于测试的main()函数
int main()
{
Complex c1(3,4),c2(5,-10),c3;
double i=10;
cout<<"c1=";
c1.display();
cout<<"c2=";
c2.display();
cout<<"i="<<i<<endl;
c3=c1+c2;
cout<<"c1+c2=";
c3.display();
cout<<"c1+i=";
(c1+i).display();
cout<<"i+c1=";
(i+c1).display();
c3=c1-c2;
cout<<"c1-c2=";
c3.display();
cout<<"c1-i=";
(c1-i).display();
cout<<"i-c1=";
(i-c1).display();
c3=c1*c2;
cout<<"c1*c2=";
c3.display();
cout<<"c1*i=";
(c1*i).display();
cout<<"i*c1=";
(i*c1).display();
c3=c1/c2;
cout<<"c1/c2=";
c3.display();
cout<<"c1/i=";
(c1/i).display();
cout<<"i/c1=";
(i/c1).display();
return 0;
}

运行结果：



知识点总结：记住当运算符重载函数不是成员函数时，要用友元函数声明，并且形参数为两个你，都不能省略，同时要求运算符左侧的操作数与函数第一个参数对应，运算符右侧的操作数与函数第二个参数对应，故“复数+实数”与“实数+复数”所声明定义的函数是不一样的；再者当运算符重载函数是成员函数时，只用写一个形参即可，但要求运算符左侧的操作数即运算表达式中的第一个参数是一个类对象，而且与运算符重载函数的类型相同。

学习心得：看的眼睛花，写的眼睛痛，最后写main函数又有点卡了，于是看了下老师的，懂了！