一、运算符重载
格式：[返回值类型] operator[被重载运算符](同返回值类型& [形参]){}

• Complex c(1,2);
• Complex c2(3,4);
• c.Plus(c2);
• c+c2;
• 注：对于本节调用函数时，this指向的是c,函数中real是c的，c.real是c2的
• 谁在前谁就是this所指向的，在后就是c形参;

#include <iostream>
#include <cmath>

using namespace std;

/*
 * @brief 复数
 */
class Complex{
private:
    // 成员变量
    float real;// 实部
    float imag;// 虚部
public:
    Complex(float r = 0,float i = 0){
        Init(r,i);
    }
    // 成员函数
    // 初始化
    void Init(float r,float i){
        real = r;
        imag = i;
    }
    // 加
    Complex Plus(Complex c){
        Complex res;
        // 在类内部,可以直接访问本类的其他对象的所有成员.
        res.real = real + c.real;
        res.imag = imag + c.imag;
        return res;
    }
    Complex operator+(const Complex& c)const{
        Complex res;
        res.real = real + c.real;
        res.imag = imag + c.imag;
        return res;
    }
    Complex Plus(const Complex* p){
        Complex res;
        res.real = real + p->real;
        res.imag = imag + p->imag;
        return res;
    }

    // 减
    Complex Divide(Complex c){
        Complex res;
        // 在类内部,可以直接访问本类的其他对象的所有成员.
        res.real = real - c.real;
        res.imag = imag - c.imag;
        return res;
    }
    Complex operator-(const Complex& c)const{
        Complex res;
        // 在类内部,可以直接访问本类的其他对象的所有成员.
        res.real = real - c.real;
        res.imag = imag - c.imag;
        return res;
    }
    Complex operator-()const{
        Complex res;
        res.real = -real;
        res.imag = -imag;
        return res;
    }
    Complex operator+()const{
        return *this;
    }
    // 乘
    // 除
    // 取模
    float Mode(){
        return sqrt(real*real+imag*imag);
    }
    // 相等
    bool Equal(Complex c){
        return real == c.real && imag == c.imag;
    }
    bool operator==(const Complex & c) const{
        return real == c.real && imag == c.imag;
    }
    // 不相等
    bool NotEqual(Complex c){
        return !Equal(c);
    }
    bool operator!=(const Complex& c) const{
        return !(*this == c);
    }
    // 打印
    void Print(){
        cout << real;
        if(imag > 0){
           cout<< "+";
        }
        cout << imag << "i" << endl; 
    }
    friend ostream& operator<<(ostream& os,const Complex& c);
};
    ostream& operator<<(ostream& os,const Complex& c){
        os << c.real;
        if(c.imag > 0){
            os<< "+";
        }
        os << c.imag<< "i" << endl;
//      return os;
    }

int main(){
    Complex c(3,4);
    // Complex c;// 报错
    // c.Init(3,4);
    c.Print();
    cout << c << endl;
    
    Complex c1;
    c1.Init(5,9);
    c1.Print();

    Complex res = c.Divide(c1);
    res.Print();

    Complex res1 = c1.Divide(c);
    res1.Print();

    cout << c.Equal(c1) << endl;
    cout << c.Equal(c) << endl;

    // c + c1 - c
    c.Plus(&c1).Divide(c).Print();
    c.operator+(c1).operator-(c).Print();
    (c+c1-c).Print();
    
    cout << (c==c1) << endl;
    cout << (c1==c1) << endl;
    const Complex c2(3,4);
    cout << (c2 == c) << endl;
//  (-c2).Print();
    cout << (-c2) <<endl;
    (cout << (-c2)) << endl;
}