重载加法运算符以添加两个多项式

Posted 2023-02-16

【中文标题】重载加法运算符以添加两个多项式

【英文标题】：Overload addition operator to add two polynomials

【发布时间】：2016-10-28 15:49:13

【问题描述】：

我正在尝试。我的想法是将多项式制作为两个数组，一个用于系数，一个用于指数。添加两个多项式只是将两个数组组合成一个更长的数组。我刚刚学习了指针和 & 符号，但不知道如何有效地使用它们。我收到错误消息说“表达式必须是可修改的左值”。

getter 和 setter 函数将用于组合相同指数的项，我还没有写。

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

Polynomial::Polynomial()

;

Polynomial Polynomial::operator + (const Polynomial &right) const

    Polynomial Sum;
    Sum.numberOfTerms = numberOfTerms + right.numberOfTerms;
    int i = static_cast<int>(numberOfTerms);
    int j = static_cast<int>(right.numberOfTerms);
    for (int n = 0; n > i && n <= n + j; n++) 
        coefficients[n] = right.coefficients[n]; //error saying expression must be a modifiable lvalue
        exponents[n] = right.exponents[n];
    
    return Sum;


    void Polynomial::enterTerms() 
    int coefficient=0;
    int exponent=0;

    cout << "Enter number of terms for the polynomial:";
    cin >> numberOfTerms;

    for (int i = 0; i < numberOfTerms; i++) 
        cout << "Enter coefficient:\n";
        cin >>coefficient;
        coefficients[i] = coefficient;

        cout << "Enter exponent:\n";
        cin >> exponent;
        exponents[i] = exponent;
    


void Polynomial::printPolynomial() const 
    //Print the first term out, if exponent is 0, just print out the     constant
    if (exponents[0] == 0) 
        cout << coefficients[0];
    
    else
        cout << coefficients[0] << "x^" << exponents[0];
    

    //Print from the second term to the last term, including a "+" in front of each term
    for (int i = 1; i <= numberOfTerms; i++) 
        if (exponents[i] == 0) 
            cout <<"+"<< coefficients[i];
        
        else 
            cout << "+"<<coefficients[i] << "x^" << exponents[i];
        

    


int Polynomial::getNumberOfTerms() const 
    return numberOfTerms;


int Polynomial::getTermCoefficient(int i) const 
    return coefficients[i];


int Polynomial::getTermExponent(int i) const 
    return exponents[i];

这是头文件

#ifndef POLYNOMIAL_H
#define POLYNOMIAL_H
#include <array>
using namespace std;

class Polynomial 
public:
    static const int maxTerms = 100;

    Polynomial();

    Polynomial operator+(const Polynomial &)const;

void enterTerms();
    void printPolynomial() const;
    int getNumberOfTerms() const;
    int getTermExponent(int) const;
    int getTermCoefficient(int) const;

void setCoefficient(int, int);
//~Polynomial();


private:
    size_t numberOfTerms;
    array<int, maxTerms> exponents;
    array<int, maxTerms> coefficients;
    static void polynomialCombine(Polynomial &);
;
#endif

【参考方案1】：

您已将运算符 + 声明为 const：

Polynomial Polynomial::operator + (const Polynomial &right) const
                                                            ^^^^^

这意味着 this-> 系数[*] 不能被修改。即您创建了一个 Sum 对象，但正尝试写入 *this 而不是您返回的 Sum 对象。

【讨论】：

谢谢！但是无论如何将两个系数和指数数组与将运算符 + 声明为 const 结合起来？

您可以使用非成员函数（可能声明为友元）：多项式运算符 + ( const Polynomial &, const Polynomial & ) ;

但是这个Polynomial operator + ( const Polynomial &, const Polynomial & ) 不是另一个接受两个参数的运算符重载函数吗？

我已经澄清了我的回应。

现在我明白了！谢谢！