Question

我正在研究一个表示多项式的简单类。我在x矢量中存储x的系数和等效功率。分配某些术语的方式必须如测试文件中所示。它需要我提供的一些操作员超载。问题在于它除了最后一个之外还分配了适当的系数，另外每个项都具有第一个赋值的x的幂。

期望的输出：

多项式p1：2x ^ 3 + 3.6x + 7x ^ 0

多项式p2：3x ^ 1 + 6x ^ 2 + 1x ^ 4

实际输出：

多项式p1：5x ^ 3 + 2x ^ 3 + 3.6x ^ 3

多项式p2：5x ^ 1 + 3x ^ 1 + 6x ^ 1

你知道这是怎么回事吗？我

Polynomials.cpp

double & Polynomials::operator[]( int power_of_x ){


    this->coeff_and_power.push_back(5.0);  // dummy variable 5.0 just to alloc 'cell' for coefficient

    this->coeff_and_power.push_back( (double) power_of_x ); //assigning power of x

    this->polynomial_terms.push_back( coeff_and_power );    // polynomial_terms vector contains collection of 2 elements vectors( coefficient and power ) indicating certain term of a function


    return (coeff_and_power[0]);  //coefficient to be assigned in main(returning by reference) function
}



std::ostream& operator<<(std::ostream& out, const Polynomials & toWrite){


    for(unsigned int i = 0; i < toWrite.polynomial_terms.size(); i++){

            if(i){
                out<<" + ";
            }

            out<<toWrite.polynomial_terms[i][0]<<"x^"<<toWrite.polynomial_terms[i][1];          
    }

    return out;
}

TEST.CPP

#include <iostream>
#include "Polynomials.h"

using namespace std;

int main(void) {

Polynomials p1;                             
p1[3] = 2; p1[1] = 3.6; p1[0] = 7;                

Polynomials p2;                            
p2[1] = 3; p2[2] = 6; p2[4] = 1;                 

cout << "Polynomial p1: " << p1 << endl;              
cout << "Polynomial p2: " << p2 << endl;

}

Answer 1

在你的operator[]超载你push_back()，但无条件。

return coeff_and_power[0];

返回front进行作业

顺便说一句

this->polynomial_terms.push_back( coeff_and_power )

推送副本而不是引用，因为polynomial_terms具有例如行为， STD：矢量

2D矢量忽略指定的值？

1 个答案: