项目一利用友元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;}
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)
{
Complex c;
c.real=c1.real+c2.real;
c.imag=c1.imag+c2.imag;
return c;
}
Complex operator-(Complex &c1,Complex &c2)
{
Complex c;
c.real=c1.real-c2.real;
c.imag=c1.imag-c2.imag;
return c;
}
void Complex::display()
{
cout<<"("<<real<<","<<imag<<"i"<<")"<<endl;
}
Complex operator*(Complex &c1,Complex &c2)
{
Complex c3;
c3.real=c1.real*c2.real-c1.imag*c2.imag;
c3.imag=c1.imag*c2.real+c1.real*c2.imag;
return c3;
}
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();
return 0;
}