2018.6.3（运算符重载）

视频教程（北大mooc）：
https://www.icourse163.org/learn/PKU-1002029030?tid=1002785058#/learn/content?type=detail&id=1003870385&cid=1004682687&replay=true
菜鸟教程：
http://www.runoob.com/cplusplus/cpp-overloading.html

/*
运算符重载形式
返回值类型 operator 运算符（形参表）
{

}
*/

#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;

class Complex
{
public:
    double real,image;
public:
    Complex(double real=0,double image=0);
    void Print();
    Complex operator+(const Complex &complex1)//重载为成员函数时，参数个数为运算符目数减一
    {
        Complex complex;
        complex.real=this->real+complex1.real;
        complex.image=this->image+complex1.image;
        return complex;//返回一个临时对象
    }
};
Complex operator -(const Complex &complex1,const Complex &complex2)//重载为普通函数时，参数个数为运算符目数
{
    Complex complex;
    complex.real=fabs(complex1.real-complex2.real);//real和image须为公有成员；
    complex.image=fabs(complex1.image-complex2.image);
    return complex;//返回一个临时对象
}
Complex::Complex(double real,double image)
{
    this->real=real;
    this->image=image;
}
void Complex::Print()
{
    printf("real=%.2f,image=%.2f\n",this->real,this->image);
}
int main()
{
    Complex complex1(1,2);
    Complex complex2(3,4);
    Complex complex3(0,0);

    complex3=complex1+complex2;//等价于complex3=complex1.operator+(complex2);因为operator+定义成了成员函数；
    complex3.Print();
    complex3=complex1-complex2;//等价于complex3=operator-(complex1,complex2);因为operator-定义成了普通函数；
    complex3.Print();

    return 0;
}