运算符重载（使用二元友元函数）class没有成员，且成员不可访问

Question

在做有关运算符重载的 youtube 教程时，我无法修复运算符重载（使用友元函数）错误消息。收到的消息是关于 class Complex 没有成员 "operator+" 和 class "Complex::real" 在第 7 行声明的是不可访问的。

// link 我正在努力学习的教程 https://www.youtube.com/watch?v=AlCYu_mc-T8

// 错误信息从这里开始://

#include "stdafx.h"
#include <iostream>
using namespace std;

class Complex
{
    int real, imag;
public:
    void read();
    void show();
    friend Complex operator+ (Complex , Complex); // Friend function declaration
};

void Complex::read()
{
    cout << "Enter real value: ";
    cin >> real;
    cout << "Enter imaginary value: ";
    cin >> imag;
}

void Complex::show()
{
    cout << real;
    if (imag < 0)
        cout << "-i";
    else
        cout << "+i";
    cout << abs(imag) << endl;
}

Complex Complex::operator+(Complex c1, Complex c2)
{
    Complex temp;
    temp.real = c1.real + c2.real;
    temp.imag = c1.imag + c2.imag;
    return temp;
}

int main()
{
    Complex c1, c2, c3;
    c1.read();
    c2.read();
    c3 = c1 + c2; // invokes operator + (Complex, Complex)
    cout << "Addition of c1 and c2 = ";
    c3.show();
    return 0;
}

Answer 1

friend 不是会员。因此，更改此行：

Complex Complex::operator+(Complex c1, Complex c2)

至：

Complex operator + (Complex c1, Complex c2)

运算符重载（使用二元友元函数）class没有成员，且成员不可访问

operator overloading(using binaray friend function) class has no member, and member inaccessible

c++

overloading

function

friend

operator-keyword