Question

我一直在创建一个名为Complex的类来存储和处理复数。我遇到的问题是我的重载+和*函数返回了一个非常大的数字，我只能假设它与指针有关，但我很擅长使用它们。我在这里复制了输出：

c1: 1 - i5
c2: -4 + i3
c1 + c2: -9.25596e+061 - i9.255
c1 * c2: -9.25596e+061 - i9.255
Press any key to continue . . .

这是类架构：

// Complex.h
#include <iostream>
#include <cmath>    
using namespace std;

class Complex
{
    friend std::ostream &operator<<(std::ostream &, const Complex &);
    friend std::istream &operator>>(std::istream &, Complex &);
    friend Complex &operator+(const Complex &, const Complex &);
    friend Complex &operator+(const Complex &, const double &);
    friend Complex &operator+(const double &, const Complex &);
    friend Complex &operator*(const Complex &, const Complex &);
    friend Complex &operator*(const Complex &, const double &);
    friend Complex &operator*(const double &, const Complex &);
public:
    explicit Complex(double re=0, double im=0);
    void setReal(double re);
    void setImag(double im);
    double &getReal();
    double &getImag();
    ~Complex();
private:
    double real;
    double imag;
};

在这里，我有我的计划的相关部分：

// Complex.cpp
#include "Complex.h"

ostream &operator<<(ostream &output, const Complex &num)
{
    output << num.real << (num.imag >= 0 ? " + i" : " - i") << abs(num.imag);
    return output;
}

Complex &operator+(const Complex &num1, const Complex &num2)
{
    Complex sum(num1.real + num2.real, num1.imag + num2.imag); // Create new complex by summing elements
    return sum;
}

Complex &operator*(const Complex &num1, const Complex &num2)
{
    Complex prod(num1.real * num2.real - num1.imag * num2.imag, num1.real * num2.imag + num1.imag * num2.real); // Create new complex by expansion
    return prod;
}

Complex::Complex(double re, double im)
{
    real = re;
    imag = im;
}

int main() {
    Complex c1(1.0, -5.0);
    Complex c2(-4.0, 3.0);
    cout << "c1: " << c1 << endl;
    cout << "c2: " << c2 << endl;
    cout << "c1 + c2: " << c1 + c2 << endl;
    cout << "c1 * c2: " << c1 * c2 << endl;
    system("pause");
}

我觉得很难打扰你们。您是否知道一个能够很好地解释C ++概念的站点，如指针，最小特权，多态，继承等？

很抱歉在这里提出基本问题，但很难找到解释这些内容的资源。

Answer 1

问题是大多数重载运算符都返回对本地var的引用，当操作符函数返回时会被销毁，从而留下悬空引用。尝试更改您的运算符以返回Complex而不是Complex &：

Complex operator+(const Complex &num1, const Complex &num2)
{
    Complex sum(num1.real + num2.real, num1.imag + num2.imag); // Create new complex by summing elements
    return sum;
}

Answer 2

错误的退货类型：

Complex &operator+(const Complex &num1, const Complex &num2)
^^^^^^^^^

您正在创建一个临时Complex并通过引用返回它，然后它会被销毁，因此您有一个悬空引用。由于operator+正在构建一个新对象并返回它，它应该通过 value 返回它...所以签名应该是：

Complex operator+(Complex const&, Complex const& );

重载运算符C ++的逻辑错误

2 个答案: