C++中的一元否定

Unary Negation in C++

本文关键字:一元 C++      更新时间:2023-10-16

我几乎完成了这个程序,但在应用一元否定函数时遇到了问题。

我制作了一个基于计算复数的程序,到目前为止,它运行得很好,除了整个负数部分。我似乎不知道如何让我的一元否定在代码中工作,而不让它警告我,并用它的运行时错误崩溃。

在我的h文件中,我有这个:

Complex operator-(const Complex &lhs);

在我的cpp文件中,我试图从上面写的内容创建这个:

Complex operator-(const Complex &lhs)
{
    return Complex(-lhs);
}

我在cpp文件上写的代码给了我一个警告C4717错误,上面写着:"operator-':在所有控制路径上递归,函数将导致运行时堆栈溢出。"当然,应用上面的数字会导致运行时错误。

我相信你们中的一些人想要完整的代码,所以这里是:header、cpp和测试文件。:)

我很感激你的帮助。

头文件:

#ifndef com_H
#define com_H
#include <iostream>
#include <string>
using namespace std;

/********** CLASS **********/
class Complex
{
    //The BFFs: Stream Insertion and Operators//
    friend istream &operator >> (istream &lhs, Complex &rhs);
    friend ostream &operator << (ostream &lhs, const Complex &rhs);
private:
    float real, img;
public:
            //Complex Constructor//
    Complex(float new_real = 0.0, float new_img = 0.0);
            //Complex Set-and-Get Functions//
    void setComplex(float new_real, float new_img);
    float getReal() const { return real; }
    float getImg()  const { return img; }
            //Complex Functions//
    Complex &operator+=(const Complex &rhs);
    Complex &operator-=(const Complex &rhs);
    Complex &operator*=(const Complex &rhs);
    Complex &operator/=(const Complex &rhs);
};

/********** O P E R A T O R **********/

Complex operator+(const Complex &lhs, const Complex &rhs);
Complex operator-(const Complex &lhs, const Complex &rhs);
Complex operator*(const Complex &lhs, const Complex &rhs);
Complex operator/(const Complex &lhs, const Complex &rhs);
//COMPARISON OPERATORS*/
bool operator==(const Complex &lhs, const Complex &rhs);
bool operator!=(const Complex &lhs, const Complex &rhs);
bool operator<(const Complex &lhs, const Complex &rhs);
bool operator<=(const Complex &lhs, const Complex &rhs);
bool operator>(const Complex &lhs, const Complex &rhs);
bool operator>=(const Complex &lhs, const Complex &rhs);
//NEGATION//
Complex operator-(const Complex &lhs);
#endif

cpp文件:

#include <iostream>
#include <string>
#include <stdlib.h>
#include <math.h>
#include "com.h"
using namespace std;
//
//***************** COMPLEX CONSTRUCTORS *****************//
//
Complex::Complex(float new_real, float new_img)
{
    real = new_real;
    img = new_img;
}
void Complex::setComplex(float new_real, float new_img)
{
    real = new_real;
    img = new_img;
}

//
//***************IF REAL NUMBER IS ZERO CHECK***************//
//
void checkNum(char ops, float new_img)
{
    char i = 'i';
    if (new_img == 0)
    {
        cout << "0";
    }
    else if (new_img != 1 && ops == '-')
    {
        new_img *= -1;
        cout << new_img << i;
    }
    else if (new_img == 1 && ops == '-')
    {
        cout << "-i";
    }
    else if (new_img == 1)
    {
        cout << i;
    }
    else
    {
        cout << new_img << i;
    }
}
//
//*****************STREAM INSERTIONS*****************//
//
istream &operator >> (istream &lhs, Complex &rhs)
{
    char ops;
    char i = 'i';
    lhs >> rhs.real >> ops >> rhs.img >> i;     //lhs is another name for cin
    if (ops == '-')
    {
        rhs.img *= -1;
    }
    return lhs;
}
ostream &operator << (ostream &lhs, const Complex &rhs)
{
    char ops;
    char i = 'i';
    float new_real = rhs.real;
    float new_img = rhs.img;
    if (new_img < 0)
    {
        ops = '-';
        new_img *= -1;
    }
    else if (new_img >= 0)
    {
        ops = '+';
    }
    if (new_real == 0)
    {
        checkNum(ops, new_img);
        return  lhs << endl;
    }
    else if (new_img == 0)
    {
        return lhs << new_real;
    }
    else if (new_img == 1)
    {
        return lhs << new_real << " " << ops << " " << i;
    }
    else
    {
        return lhs << new_real << " " << ops << " " << new_img << i;
    }
    //  lhs << rhs.real << " + " << rhs.img << 'i';
}
//
//***************COMPLEX ARITHMETIC OPERATORS***************//
//***************** ( + | - | * | / |) ***************** //
//
// FORMULA for COMPLEX NUMBERS :: (a + bi)
Complex operator+(const Complex &lhs, const Complex &rhs)
{
    float a = lhs.getReal();
    float b = lhs.getImg();
    float c = rhs.getReal();
    float d = rhs.getImg();
    return Complex(a + c, b + d);
}
Complex operator-(const Complex &lhs, const Complex &rhs)
{
    float a = lhs.getReal();
    float b = lhs.getImg();
    float c = rhs.getReal();
    float d = rhs.getImg();
    return Complex(a - c, b - d);
}

Complex operator*(const Complex &lhs, const Complex &rhs)
{
    float a = lhs.getReal();
    float b = lhs.getImg();
    float c = rhs.getReal();
    float d = rhs.getImg();
    return Complex(((a * c) - (b * d)) , ((a * d) + (b * c)));

}
Complex operator/(const Complex &lhs, const Complex &rhs)
{
    float a = lhs.getReal();
    float b = lhs.getImg();
    float c = rhs.getReal();
    float d = rhs.getImg();
    //Numerator
    float myReal = (a * c) + (b * d);
    float myImg = (b * c) - (a * d);
    //Denominator
    float myDenom = (pow(c, 2) + pow(d, 2));
    return Complex(myReal / myDenom, myImg / myDenom);
}
//
//*****************COMPLEX OPERATORS EQUALS *****************//
//**************** ( += | -=  | *= | /= |) ***************** //
//
Complex &Complex::operator+=(const Complex &rhs)
{
    real += rhs.real;
    img += rhs.img;
    //*this = *this + rhs;
    return *this;
}
Complex &Complex::operator-=(const Complex &rhs)
{
    real -= rhs.real;
    img -= rhs.img;
    return *this;
}
Complex &Complex::operator*=(const Complex &rhs)
{
    real *= rhs.real;
    img *= rhs.img;
    return *this;
}
Complex &Complex::operator/=(const Complex &rhs)
{
    real /= rhs.real;
    img /= rhs.img;
    return *this;
}

//
//******************COMPLEX OPERATORS COMPARISON*****************//
//**************** ( == | != | < | <= | > | >= |)*****************//
//
bool operator==(const Complex &lhs, const Complex &rhs)
{
    if (lhs.getReal() == rhs.getReal() && lhs.getImg() == rhs.getImg())
    {
        return true;
    }
    return false;
}
bool operator!=(const Complex &lhs, const Complex &rhs)
{
    return !(lhs == rhs);
}
bool operator<(const Complex &lhs, const Complex &rhs)
{
    if (lhs.getReal() <  rhs.getReal() || lhs.getReal() == rhs.getReal() && lhs.getImg() < rhs.getImg())
    {
        return true;
    }
    return false;
}
bool operator<=(const Complex &lhs, const Complex &rhs)
{
    return ((lhs < rhs) || (lhs == rhs));
}
bool operator>(const Complex &lhs, const Complex &rhs)
{
    return !(lhs <= rhs);
}
bool operator>=(const Complex &lhs, const Complex &rhs)
{
    return !(lhs < rhs);
}
Complex operator-(const Complex &lhs)
{
    return Complex(-lhs);
}

主文件:

#include <iostream>
#include "com.h"
#include <string>
using namespace std;
int  main()
{
    Complex  userValue;
    cout << "Enter a complex value (a + bi): ";
    cin >> userValue;
    cout << "Negated: " << -userValue << endl;
    cout << "Addition:  " << userValue + Complex(0.0, 0.0) << endl;
    if (Complex(-6, 5.2f) == userValue)
        cout << "Wow! It's equal." << endl;
    return  0;
}

更新1:哇!我刚刚再次测试了它,它实际上在我输入的任何数字上都崩溃了,阳性和阴性哈哈!但当我评论以下代码时。。。来自主

//  cout << "Negated: " << -userValue << endl;

来自头文件

Complex operator-(const Complex &lhs); 

来自cpp文件

Complex operator-(const Complex &lhs)
{
    return Complex(-lhs);
}

它仍然有效(当然没有负数)

正如错误所说,您正在递归地调用重载函数。相反,您希望使用正确的参数调用构造函数:

Complex operator-(const Complex &lhs)
{
    return Complex(-lhs.real, -lhs.imag);
}