(3)-友元 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+(double &d,Complex &c2);
    friend Complex operator-(double &d,Complex &c2);//友元函数 两个参数
    friend Complex operator*(double &d,Complex &c2);
    friend Complex operator/(double &d,Complex &c2);
    void display();
private:
    double real;
    double imag;
};
//下面定义成员函数
Complex operator+(double &d,Complex &c2)//不加Complex::
{
    return Complex(d+c2.real,c2.imag);
}
Complex operator-(double &d,Complex &c2)
{
    return Complex(d-c2.real,c2.imag);
}
Complex operator*(double &d,Complex &c2)
{
    Complex c;
    c.real=d*c2.real;
    c.imag=d*c2.imag;
    return c;
}
Complex operator/(double &d,Complex &c2)
{
    Complex c;
    c.real=d/c2.real;
    c.imag=d/c2.imag;
    return c;
}
void Complex::display()
{
    cout<<"("<<real<<","<<imag<<"i)"<<endl;
}

//下面定义用于测试的main()函数
int main()
{
    double d=6;
    Complex c2(5,-10),c3;
    cout<<"d="<<d<<endl;
    cout<<"c2=";
    c2.display();
    c3=d+c2;
    cout<<"c1+c2=";
    c3.display();
    c3=d-c2;
    cout<<"c1-c2=";
    c3.display();
    c3=d*c2;
    cout<<"c1*c2=";
    c3.display();
    c3=d/c2;
    cout<<"c1/c2=";
    c3.display();
    return 0;
}

运行结果：