c++ - 重载运算符 C++，复数？

Question

我有这么大的问题。我写了一个关于复数的程序。该程序读取和写入复数，将它们相加等。
他说我应该读一下 Why should I overload a C++ operator as a global function (STL does) and what are the caveats?和

1) 我必须创建 5 个运算符，它们是类的成员函数，并且有一个参数:+、-、!、++、--。然后

2) 我必须创建 5 个运算符，它们是类的成员函数，其中有两个参数:=、+=、-=、*=、/=；然后

3) 我必须创建 8 个运算符，它们是全局友元函数 +、-、*、/、==、!=、<<、>> 并接受两个参数。我对最后一个没有问题:

    friend const Comp operator+(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real + y.real;
        temp.imag = x.imag + y.imag;
        return temp;
    }
    friend const Comp operator-(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real - y.real;
        temp.imag = x.imag - y.imag;
        return temp;
    }
    friend const Comp operator*(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real * y.real;
        temp.imag = x.imag * y.imag;
        return temp;
    }
    friend const Comp operator/(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real / y.real;
        temp.imag = x.imag / y.imag;
        return temp;
    }

除了这个？？？？？？我应该在这里返回什么？？？？？？当我比较它应该是 bool 是吗？？？？

    friend const Comp operator==(const Comp& x, const Comp& y)
    {

    }
    friend const Comp operator!=(const Comp& x, const Comp& y)
    {

    }

我认为我找到了解决方案

    friend bool operator==(const Comp& x, const Comp& y)
    {
            return (x.real == y.real && x.imag == y.imag);
    }
    friend bool operator!=(const Comp& x, const Comp& y)
    {
            return (x.real != y.real && x.imag != y.imag);
    }

这是我的全部代码

#include <fstream>
#include <cstdlib> 
#include <iostream>
#include <iomanip>
#include <cmath>
#ifndef M_PI
    #define M_PI 3.14159265358979323846
#endif
using namespace std;


class Comp {
    double real, imag;

public:
    Comp(){
    real;
    imag;
    }
    double re(void) const
    {
        return real;
    }
    double im(void) const
    {
        return imag;
    }
    double mod(void) const
    {
        return sqrt(re()*re() + im()*im());
    }
    double arg(void) const
    {
        double faza;
        if (im() >= 0)
            faza = acos(re()/mod());
        else
            faza = 2*M_PI - acos(re()/mod());

    return faza;
    }
    const Comp conj(void) const
    {
        Comp temp;
        -im();
        return temp;
    }
    ~Comp(){}
    /*
    Comp operator+(const Comp& x);
    Comp operator-(const Comp& x);
    bool operator!(void);
    const Comp& operator++();
    const Comp operator++(int);
    const Comp& operator--();
    const Comp operator--(int);
    Comp operator=(const Comp x);
    Comp operator-=(const Comp& x);
    Comp operator+=(const Comp& x);
    Comp operator*=(const Comp& x);
    Comp operator/=(const Comp& x);
    */
    friend const Comp operator+(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real + y.real;
        temp.imag = x.imag + y.imag;
        return temp;
    }
    friend const Comp operator-(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real - y.real;
        temp.imag = x.imag - y.imag;
        return temp;
    }
    friend const Comp operator*(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real * y.real;
        temp.imag = x.imag * y.imag;
        return temp;
    }
    friend const Comp operator/(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real / y.real;
        temp.imag = x.imag / y.imag;
        return temp;
    }
    friend const Comp operator==(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real + y.real;
        temp.imag = x.imag + y.imag;
        return temp;
    }
    friend const Comp operator!=(const Comp& x, const Comp& y)
    {
        Comp temp;
        temp.real = x.real + y.real;
        temp.imag = x.imag + y.imag;
        return temp;
    }

    friend std::ostream& operator<<(std::ostream& wart1,  const Comp& a)
    {
        return wart1 <<fixed << setprecision(2) << '(' << a.re() << "," << a.im() << ')' << ' ' << endl;
    }
    friend std::istream& operator>>(std::istream& wart2, Comp& b){
        char c;
        return wart2>>c>>b.real>>c>>b.imag>>c; 
    }
};

int main(int argc, char* argv[])
{ 
    ifstream read(argv[1]);
    if (!read)
        { cerr << "Open error: " << argv[1] << endl; exit(1);}
    ofstream write(argv[2]);

    if(!write) { cerr << "Open error: " << argv[2] << endl; exit(2);} 
    read.clear();
    read.seekg(0);
    Comp x1;
    read >> x1;
    write << x1;
    cout << x1;
    Comp x2;
    read >> x2;
    write << x2;
    cout << x2;
    cout << x1.mod() << endl;
    cout << x2.mod() << endl;
    cout << x1.arg() << endl;
    cout << x2.arg() << endl;
    cout << x1.conj();
    cout << x2.conj();
    write << x2;
    write << x1.mod() << endl;
    write << x2.mod() << endl;
    write << x1.arg() << endl;
    write << x2.arg() << endl;
    write << x1.conj();
    write << x2.conj();
    Comp sum;
    sum = x1 + x2;
    cout << sum;
    write << sum;
    Comp sub;
    sub = x1 - x2;
    cout << sub;
    write << sub;
    Comp mult;
    mult = x1 * x2;
    cout << mult;
    write << mult;
    Comp div;
    div = x1 / x2;
    cout << div;
    write << div;

    return 0;
}  

Answer 1

如果您实现 operator==正确(您在标题为“我认为我找到解决方案”的 block 中所做的)，然后您可以将它用于 operator!= :

friend bool operator!=(const Comp& x, const Comp& y)
{
    return !(x == y);
}

您的版本不正确，因为如果它们具有相同的实部和不同的虚部，它将报告它们不相等。

此外，在第 (1) 部分中，它指的是一元 + 和 -(不是我们在第 3 部分中获得的二进制版本)。所以你在注释掉的 block 中的前两个声明是不正确的，它们应该是:

Comp operator+();
Comp operator-();