8-1-3运算符重载（扩展+，-..功能，定义一目运算符“-”）

/* (程序头部注释开始)
* 程序的版权和版本声明部分
* Copyright (c) 2011, 烟台大学计算机学院学生
* All rights reserved.
* 文件名称： 复数类中的运算符重载
* 作 者： 张传新
* 完成日期： 2012 年 04 月 07 日
* 版 本 号： V.1.0

* 对任务及求解方法的描述部分
* 问题描述：实现复数类中的运算符重载,定义一个复数类重载运算符+、-、*、/，使之能用于复数的加减乘除。
在方案二的基础上，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运算的结果（其中?为+、-、*、/之一）。另外，定义一目运算符-，-c相当于0-c。
* 程序头部的注释结束

#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 + (Complex &c1,Complex &c2);//复数加法friend Complex operator - (Complex &c1,Complex &c2);//复数减法friend Complex operator * (Complex &c1,Complex &c2);//复数乘法friend Complex operator / (Complex &c1,Complex &c2);//复数除法friend Complex operator + (Complex &c1,const double &i);//复数加非复数friend Complex operator + (const double &i,Complex &c1);//非复数加复数friend Complex operator - (Complex &c1);//定义一目运算符“-”void display();private:double real;double imag;};//下面定义成员函数void Complex::display(){cout << "(" << real << ","  << imag << "i)" << endl;}//复数加法Complex operator + (Complex &c1,Complex &c2) { return Complex(c1.real + c2.real,c1.imag + c2.imag); }//复数减法Complex operator - (Complex &c1,Complex &c2) { return Complex(c1.real - c2.real,c1.imag - c2.imag); }//复数乘法Complex operator * (Complex &c1,Complex &c2) { return Complex(c1.real * c2.real - c1.imag * c2.imag,c1.imag * c2.real + c1.real * c2.imag); }//复数除法Complex operator /  (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));   }//复数与double型相加Complex operator+(Complex &c1,const double &i)  {      return Complex(c1.real + i,c1.imag);  }  //double型与复数相加Complex operator+(const double &i,Complex &c1)  {      return Complex(c1.real + i,c1.imag);  }  //定义一目运算符“-”Complex operator - (Complex &c1){return Complex(-c1.real,-c1.imag);} void main() { Complex c1(3,4),c2(5,-10),c3; cout<<"c1 = ";       c1.display();       cout<<"c2 = ";       c2.display();   c3 = c1 + c2; cout << "c1 + c2 = "; c3.display(); c3 = c1 - c2; cout << "c1 - c2 = "; c3.display(); c3 = c1 * c2;  cout << "c1 * c2 = "; c3.display(); c3 = c1 / c2; cout << "c1 / c2 = "; c3.display(); c3 = c1 + 1.11; cout << "c1 + 1.11 = "; c3.display(); c3 = 1.11 + c1; cout << "1.11 + c1 = "; c3.display(); c3 = -c1; cout<< "-c1 = "; c3.display(); system("pause"); }

运行结果：

经验积累：

1.重载不能改变运算符运算对象的个数。

2.重载的运算符必须和用户定义的自定义类型的对象一起

使用，其参数至少应有一个是类对象（或类对象的引用）。