11、友元函数计算2+z

#include<iostream>
using namespace std;
class Cmycomplex
{
private:
    double real,imag;
public:
    Cmycomplex(double r=0,double i=0);//构造函数设默认值，或者重载构造函数 
    void Set(double r,double i);
    Cmycomplex operator +(Cmycomplex &);//注意，这里只需要传一个参数，运算符+重载功能上类似自定义的.add()函数 
    friend Cmycomplex operator +(double r,Cmycomplex &);//友元这里传两个参数，friend关键字写在最前面 
    friend Cmycomplex operator +(Cmycomplex &,double r);//友元这里传两个参数，friend关键字写在最前面
    void Show();
};

Cmycomplex::Cmycomplex(double r,double i)//类外定义时无需再写默认值 
{
    real=r;
    imag=i;
}

void Cmycomplex::Set(double r,double i)
{
    real=r;
    imag=i;
}

Cmycomplex Cmycomplex::operator +(Cmycomplex &z) 
{
    Cmycomplex tmp;
    tmp.real=real+z.real;
    tmp.imag=imag+z.imag;
    return tmp;
}

Cmycomplex operator +(double r,Cmycomplex &z)//类外无需写friend关键字，可看作普通函数，不属于该类 
{
    Cmycomplex tmp;
    tmp.real=r+z.real;
    tmp.imag=z.imag;
    return tmp;
}

Cmycomplex operator +(Cmycomplex &z,double r)//类外无需写friend关键字，可看作普通函数，不属于该类 
{
    Cmycomplex tmp;
    tmp.real=z.real+r;
    tmp.imag=z.imag;
    return tmp;
}

void Cmycomplex::Show()
{
    cout << "(" << real << "+" << imag << "i" << ")" << endl; 
}