c++ - 动态数组 C++ 多项式类

Question

我正在尝试在 C++ 中构建一个动态数组，以使用项目的多项式类。我是 C++ 的新手，我很迷茫。我相信我已经正确分配了内存，但是我的析构函数遇到了问题，说“正​​在释放的内存没有分配。”如果我将其注释掉，它会起作用，但在那之后我迷路了。有什么想法吗？

#ifndef __Chapter9Program__Polynomial__
#define __Chapter9Program__Polynomial__

#include <iostream>
using namespace std;

class Polynomial
{
    public:
    Polynomial(int deg, int coeff[]);
    Polynomial operator+(Polynomial other);
    Polynomial operator-(Polynomial other);
    Polynomial operator*(Polynomial other);
    ostream& operator<<(ostream& os);//, const Polynomial& object);
    const int getDegree();
    const int getCoeff(const int index);
    double evaluateAt(double x); //Finds P(x)
    void show();
    string print();
    // destructor
    ~Polynomial();
private:
    int degree;
    int *coefficient; //Alllocate memory
};

#endif /* defined(__Chapter9Program__Polynomial__) */


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

//Constructor
Polynomial::Polynomial(int deg, int coeff[])
{
degree = deg;
coefficient = new int [degree];
for( int i = 0; i <= degree; i++)
{
    coefficient[i] = coeff[i];
}
}

//Destructor
Polynomial::~Polynomial()
{
if( coefficient )
{
    delete [] coefficient;
    coefficient = NULL;
}
}

//finds P(x)
double Polynomial::evaluateAt(double x)
{
double sum = 0.0;
double xPow = 1.0;
if( coefficient )
    for(int i=0; i<degree; i++)
    {
        sum += xPow*coefficient[i];
        xPow *= x;
    }

return sum;
}

Polynomial Polynomial::operator+(Polynomial other)
{
int first[degree];
int second[degree];
for(int i = 0; i< degree; i++)
{
    first[i] = 0;
    second[i] = 0;
}
int newDeg;
int temp[degree];
int final[degree];
int final2[degree];
if(degree > other.getDegree())
{
    newDeg = degree;
}
else
{
    newDeg = other.getDegree();
}
if(degree > other.getDegree())
{
    for(int i=0;i<=degree;i++)
    {
        first[i] = coefficient[degree-i];
    }
    for(int i = 0; i <= other.getDegree(); i++)
    {
        second[i] = other.getCoeff(other.getDegree()-i);
    }
    for(int i = 0; i<degree; i++)
    {
        temp[i] = first[i]+second[i];
    }
    for(int i=degree-1; i>=0; i--)
    {
        final[i] = temp[i-i];
    }
    for(int i=0;i<=newDeg;i++)
    {
        final2[i] = final[(degree-1)-(newDeg-i)];
    }
}
else if(degree == other.getDegree())
{
    for(int i=0;i<=degree;i++)
    {
        first[i] = coefficient[i];
    }
    for( int i = 0; i <= other.getDegree(); i++)
    {
        second[i] = other.getCoeff(i);
    }
    for(int i = 0; i<degree; i++)
    {
        final[i] = first[i]+second[i];
    }
    for(int i=0;i<=newDeg;i++)
    {
        final2[i] = final[(degree - 1)-(newDeg-i)];
    }
}
else
{
    for( int i = 0; i <= other.getDegree(); i++)
    {
        second[i] = other.getCoeff(other.getDegree()-i);
    }
    for(int i = 0; i <= degree; i++)
    {
        first[i] = coefficient[degree-i];
    }
    for(int i = 0; i<degree; i++)
    {
        temp[i] = first[i]+second[i];
    }
    for(int i=degree-1; i>=0; i--)
    {
        final[i] = temp[i-1];
    }
    for(int i=0;i<=newDeg;i++)
    {
        final2[i] = final[(degree - 1)-(newDeg-i)];
    }
}
return Polynomial(newDeg,final2);
}

Polynomial Polynomial::operator-(Polynomial other)
{
int first[degree];
int second[degree];
for(int i = 0; i< degree; i++)
{
    first[i] = 0;
    second[i] = 0;
}
int newDeg;
int temp[degree];
int final[degree];
int final2[degree];
if(degree > other.getDegree())
{
    newDeg = degree;
}
else
{
    newDeg = other.getDegree();
}
if(degree > other.getDegree())
{
    for(int i=0;i<=degree;i++)
    {
        first[i] = coefficient[degree-i];
    }
    for(int i = 0; i <= other.getDegree(); i++)
    {
        second[i] = other.getCoeff(other.getDegree()-i);
    }
    for(int i = 0; i<degree; i++)
    {
        temp[i] = first[i]-second[i];
    }
    for(int i=0; i<degree; i++)
    {
        final[i] = temp[(degree-1)-i];
    }
    for(int i=0;i<=newDeg;i++)
    {
        final2[i] = final[(degree - 1)-(newDeg-i)];
    }
}
else if(degree == other.getDegree())
{
    for(int i=0;i<=degree;i++)
    {
        first[i] = coefficient[i];
    }
    for( int i = 0; i <= other.getDegree(); i++)
    {
        second[i] = other.getCoeff(i);
    }
    for(int i = 0; i<degree; i++)
    {
        final[i] = first[i]-second[i];
    }
    for(int i=0;i<=newDeg;i++)
    {
        final2[i] = final[(degree - 1)-(newDeg-i)];
    }
}
else
{
    for( int i = 0; i <= other.getDegree(); i++)
    {
        second[i] = other.getCoeff(other.getDegree()-i);
    }
    for(int i = 0; i <= degree; i++)
    {
        first[i] = coefficient[degree-i];
    }
    for(int i = 0; i<degree; i++)
    {
        temp[i] = first[i]-second[i];
    }
    for(int i=0; i<degree; i++)
    {
        final[i] = temp[(degree - 1)-i];
    }
    for(int i=0;i<=newDeg;i++)
    {
        final2[i] = final[(degree - 1)-(newDeg-i)];
        //cout<<final2[i]<<endl;
    }
}
return Polynomial(newDeg,final2);
}

Polynomial Polynomial::operator*(Polynomial other)
{
int newDeg = degree + other.getDegree();
int resultCoeff[degree];
for(int i = 0; i<degree; i++)
{
    resultCoeff[i] = 0;
}
//cout<<resultCoeff[5]<<endl;
for(int i = 0; i<=degree; i++)
{
    for(int j = 0; j<=other.getDegree(); j++)
    {
        resultCoeff[i+j] += (other.getCoeff(j)*coefficient[i]);
        //cout<<i+j<<endl;
        //cout<<other.getCoeff(j)<<endl;
        //cout<<coefficient[i]<<endl;
        //cout<<resultCoeff[i+j]<<endl;
    }
}
return Polynomial(newDeg,resultCoeff);
}


string Polynomial::print()
{
string result;
int deg = degree;
for(int i = 0; i<=degree; i++)
{
    if(result == "")
    {
        //cout<<coefficient[i]<<endl;
        result = to_string(coefficient[i]);
        result += "x^";
        result += to_string(deg);
        deg -= 1;
    }
    else //if(coefficient[i] >= 0)
    {
        //cout<<coefficient[i]<<endl;
        result += "+";
        result += to_string(coefficient[i]);
        result += "x^";
        result += to_string(deg);
        deg -= 1;
    }
    //else if(coefficient[i] < 0)
    //{
        //cout<<coefficient[i]<<endl;
    //    result += "-";
    //    result += to_string(coefficient[i]);
    //    result += "x^";
    //    result += to_string(deg);
    //    deg -= 1;
    //}
}
return result;
}

const int Polynomial::getDegree()
{
return degree;
}

const int Polynomial::getCoeff(int index)
{
return coefficient[index];
}

主要

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

int main()
{
using namespace std;
int degree = 2;
int coefficients[10] = {2,3,5};
int degree2 = 3;
int coefficients2[10] = {1,5,2,3};

Polynomial test = Polynomial(degree, coefficients);
cout << &test<<endl;//.print()<<endl;
Polynomial test2 = Polynomial(degree2, coefficients2);
cout << &test2<<endl;//.print()<<endl;
Polynomial test3 = test + test2;
cout << &test3<<endl;//.print()<<endl;
Polynomial test4 = test - test2;
cout << &test4<<endl;//.print()<<endl;
Polynomial test5 = test * test2;
cout << &test5<<endl;//.print();
return 0;
}

Answer 1

您的类没有定义复制构造函数。您将需要其中之一，因为默认复制构造函数执行浅复制，它只复制指针值而不复制系数数组的内容。

当您复制您的对象时(您到处都在做)，问题就出现了，因为这两个拷贝稍后会在它们被破坏时尝试删除同一个数组。

您还需要定义一个赋值运算符。查看Rule of Three .