用友元函数实现复数类的运算符重载

#include  
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)  
{  
    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;  
}  
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;  
}  
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<<"("< }  
  
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();  
    return 0;  
}