接：第8周-任务1-方案1-复数类中运算符重载（成员函数实现）

本文用方案二求解：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；

【讲解视频】

【参考解答】

#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;
};

//复数相加：(a+bi)+(c+di)=(a+c)+(b+d)i. 
Complex operator+(Complex &c1, Complex &c2)
{
	Complex c;
	c.real=c1.real+c2.real;
	c.imag=c1.imag+c2.imag;
	return c;
}

//复数相减：(a+bi)-(c+di)=(a-c)+(b-d)i.
Complex operator-(Complex &c1, Complex &c2)
{
	Complex c;
	c.real=c1.real-c2.real;
	c.imag=c1.imag-c2.imag;
	return c;
}

//复数相乘：(a+bi)(c+di)=(ac－bd)+(bc+ad)i.
Complex operator*(Complex &c1, Complex &c2)
{
	Complex c;
	c.real=c1.real*c2.real-c1.imag*c2.imag;
	c.imag=c1.imag*c2.real+c1.real*c2.imag;
	return c;
}

//复数相除：(a+bi)/(c+di)=(ac+bd)/(c^2+d^2) +(bc-ad)/(c^2+d^2)i 
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.imag*c2.real-c1.real*c2.imag)/(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;
}

【进一步扩展】事实上，运算符重载的函数还可以定义成一般函数，只不过这种做法并不好。下面给出使用一般函数完成运算符重载的程序。其中，加了序号的3处注释值得关注。

#include <iostream>
using namespace std;
class Complex
{
public:
	Complex(){real=0;imag=0;}
	Complex(double r,double i){real=r;imag=i;}
	double getReal() const {return real;}  //(1)定义公用的数据接口，可以为const成员函数
	double getImag() const {return imag;}
	void setReal(double r){real=r;}        //(1)定义公用的数据接口
	void setImag(double i){imag=i;}


	void display();
private:
	double real;
	double imag;
};

//复数相加：(a+bi)+(c+di)=(a+c)+(b+d)i. 
Complex operator+(const Complex &c1, const Complex &c2) //(3)将参数处理为const更符合需求
{
	Complex c;
	c.setReal(c1.getReal()+c2.getReal());   //(2)调用公用数据接口读取和修改私有数据成员
	c.setImag(c1.getImag()+c2.getImag());
	return c;
}

//复数相减：(a+bi)-(c+di)=(a-c)+(b-d)i.
Complex operator-(const Complex &c1, const Complex &c2)
{
	Complex c;
	c.setReal(c1.getReal()-c2.getReal());
	c.setImag(c1.getImag()-c2.getImag());
	return c;
}

//复数相乘：(a+bi)(c+di)=(ac－bd)+(bc+ad)i.
Complex operator*(const Complex &c1, const Complex &c2)
{
	Complex c;
	c.setReal(c1.getReal()*c2.getReal()-c1.getImag()*c2.getImag());
	c.setImag(c1.getImag()*c2.getReal()+c1.getReal()*c2.getImag());
	return c;
}

//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, const Complex &c2)
{
	Complex c;
	double d= (c2.getReal()*c2.getReal()+c2.getImag()*c2.getImag());
	c.setReal((c1.getReal()*c2.getReal()+c1.getImag()*c2.getImag())/d);
	c.setImag((c1.getImag()*c2.getReal()-c1.getReal()*c2.getImag())/d);
	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;
}