第八周任务一：运算符重载

/* (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：     实现复数类中的运算符重载
* 作    者：       田庆
* 完成日期：  2012     年   4    月   7     日
* 版 本 号：

* 对任务及求解方法的描述部分
* 输入描述：
* 问题描述：定义一个复数类重载运算符+、-、*、/，使之能用于复数的加减乘除。
* 程序输出：
* 程序头部的注释结束
*/
方案一：请用类的成员函数完成运算符的重载

#include<iostream>
using namespace std;
class Complex
{
public:
Complex(){real=0;imag=0;}
Complex(double r,double i){real=r;imag=i;}
Complex operator+(Complex &c2);
Complex operator-(Complex &c2);
Complex operator*(Complex &c2);
Complex operator/(Complex &c2);
void display();
private:
double real;
double imag;
};
//用成员函数定义加减乘除
Complex Complex::operator+(Complex &c2)//下面定义成员函数
{
return(Complex(real+c2.real,imag+c2.imag));
}
Complex Complex::operator-(Complex &c2)
{
return(Complex(real-c2.real,imag-c2.imag));
}
Complex Complex::operator*(Complex &c2)
{
Complex c;
c.real = real*c2.real - imag*c2.imag;
c.imag = real*c2.imag + imag*c2.real;
return c;
}
Complex Complex::operator/(Complex &c2)
{
Complex c;
c.real = (real*c2.real + imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag);
c.imag = (-real*c2.imag + imag*c2.real)/(c2.real*c2.real+c2.imag*c2.imag);
return c;
}

void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i)"<<endl;
}
int 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();
system("pause");
return 0;
}

方案二：请用类的友元函数，而不是成员函数，完成上面提及的运算符的重载；

#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);
friend Complex operator-(Complex &c1,Complex &c2);
friend Complex operator*(Complex &c1,Complex &c2);
friend Complex operator/(Complex &c1,Complex &c2);
void display();
private:
double real;
double imag;
};
Complex operator+(Complex &c1,Complex &c2)
{
return Complex(c1.real+c2.real,c1.imag+c2.imag);
}
Complex operator-(Complex &c1,Complex &c2)
{
return Complex(c1.real-c2.real,c1.imag-c2.imag);
}
Complex operator*(Complex &c1,Complex &c2)
{
Complex c;
c.real = c1.real*c2.real - c1.imag*c2.imag;
c.imag = c1.real*c2.imag + c1.imag*c2.real;
return c;
}
Complex operator/(Complex &c1,Complex &c2)
{
Complex c;
c.real = (c1.real*c2.real + c1.imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag);
c.imag = (-c1.real*c2.imag + c1.imag*c2.real)/(c2.real*c2.real+c2.imag*c2.imag);
return c;
}
void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i)"<<endl;
}
int 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();
system("pause");
return 0;
}

方案三：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。

#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);//声明重载函数加作为友元函数
friend Complex operator-(Complex &c1,Complex &c2);//声明重载函数减作为友元函数
friend Complex operator*(Complex &c1,Complex &c2);//声明重载函数加乘作为友元函数
friend Complex operator/(Complex &c1,Complex &c2);//声明重载函数除作为友元函数
friend Complex operator+(Complex &c1,double &d); //声明重载函数第一个参数可以不是类对象,在用double型中或用double d；又或const double &d
friend Complex operator+(double &d,Complex &c1);//声明重载函数第二个参数可以不是类对象
friend Complex operator-(Complex &c2);//声明一目运算符形如"-c"
void display();
private:
double real;
double imag;
};
//定义友元函数加法
Complex operator+(Complex &c1,Complex &c2)
{
return Complex(c1.real + c2.real,c1.imag + c2.imag);
}
//定义复数加double型的数
Complex operator+(Complex &c1,double &d)
{
return Complex(c1.real + d,c1.imag);
}
Complex operator+(double &d,Complex &c1)
{
return Complex(c1.real + d,c1.imag);
}
//定义友元函数减法
Complex operator-(Complex &c1,Complex &c2)
{
return Complex(c1.real - c2.real,c1.imag - c2.imag);
}
//定义一目运算符形如"-c"
Complex operator-(Complex &c2)
{
return Complex(-c2.real, -c2.imag);
}
//定义友元函数乘法
Complex operator*(Complex &c1,Complex &c2)
{
Complex c;
c.real = c1.real*c2.real - c1.imag*c2.imag;
c.imag = c1.real*c2.imag + c1.imag*c2.real;
return c;
}
//定义友元函数除法
Complex operator/(Complex &c1,Complex &c2)
{
Complex c;
c.real = (c1.real*c2.real + c1.imag*c2.imag)/(c2.real*c2.real+c2.imag*c2.imag);
c.imag = (-c1.real*c2.imag + c1.imag*c2.real)/(c2.real*c2.real+c2.imag*c2.imag);
return c;
}
void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i)"<<endl;
}
int main()
{
double m=2.15;//用 const 或直接用d就不用再定义这个啦！直接在后面用2.15就行
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=m+c1;
cout<<"2.15+c1=";
c3.display();
c3=c1+m;
cout<<"c1+2.15=";
c3.display();
c3=-c2;
cout<<"-c2=";
c3.display();
system("pause");
return 0;
}

小结：函数重载也就是比着葫芦画个瓢，会个成员函数，再用友元函数啥的又算是温故了一番。