为什么当我试图使操作员过载时会出现链接错误

Question

我正在做一个项目练习，修改我创建的名为Polynomial的类的上一个项目，以使用链接列表(最初使用的数组(。链接列表使用一个模板，这样任何类型都可以传递到其中

我在这个项目练习中遇到的一个问题是，我试图传递一个类型为PolyNumber的对象(来自我创建的一个类(，而我创建的链接列表包有一个比较传递给它的任何项目(使用==(的函数

它适用于常规类型，如int和string，但在自定义对象类型时会遇到问题。因此，我发现了如何在PolyNumber类中重载==运算符。当我测试这个类时，它本身就起作用，但当我将这个类型与带有链表实现的Polynomial类一起使用时，我会对多项式类中的每个方法都出现以下错误：

Error   LNK2005 "public: __thiscall PolyNumber::PolyNumber(int,int)" (??0PolyNumber@@QAE@HH@Z) already defined in Polynomial.obj    Project11

这是我为这些文件编写的代码，但正如你在代码中看到的，还有其他与此代码相关的文件，例如链接列表对象的LinkedBag，但就空间而言，我只包括以下文件：

PolyNumber.h

#pragma once
class PolyNumber
{
public:
PolyNumber();
PolyNumber(int set_coefficent, int set_degree);
void setDegree(int set);
void setCoefficient(int set);
int getDegree();
int getCoefficient();
friend bool operator== (const PolyNumber& p1, const PolyNumber& p2);
friend bool operator!= (const PolyNumber& p1, const PolyNumber& p2);
private:
int degree;
int coefficient;
};

PolyNumber.cpp

#include "PolyNumber.h"

PolyNumber::PolyNumber()
{
coefficient = 0;
degree = 0;
}
PolyNumber::PolyNumber(int set_coefficent, int set_degree)
{
coefficient = set_coefficent;
degree = set_degree;
}
void PolyNumber::setDegree(int set)
{
degree = set;
}
void PolyNumber::setCoefficient(int set)
{
coefficient = set;
}
inline int PolyNumber::getDegree()
{
return degree;
}
inline int PolyNumber::getCoefficient()
{
return coefficient;
}
bool  operator== (const PolyNumber& p1, const PolyNumber& p2)
{
return (p1.coefficient == p2.coefficient && p1.degree == p2.degree);
}
bool operator!= (const PolyNumber& p1, const PolyNumber& p2)
{
return !(p1 == p2);
}

多项式.h

#pragma once
#include "PolynomialInterface.h"
#include "LinkedBag.cpp"
#include "PolyNumber.cpp"
static const int POLYNOMIAL_SIZE = 10;
class Polynomial : public Polynomoal_Interface
{
public:
//Cunstructs am empty Polynomial  
Polynomial();
//Copy constructor
Polynomial(Polynomial& copy);
/** Cunstructs a Polynomial with a client defined Polynomial
@param an array of non-negative integer coeffient that does not exceed POLYNOMIAL_SIZE, each coeffient in the array has a power that correspounds
to the respective value of the location of the ceffient in that array. */
Polynomial(int coeffient[POLYNOMIAL_SIZE], int size);
int degree();
int coefficient(int power);
bool changeCoefficient(int newCoefficient, int power);
private:
//static const int POLYNOMIAL_SIZE = 10;
//int polynomial[POLYNOMIAL_SIZE];
LinkedBag<PolyNumber> bag;
};

多项式.cpp

#include "Polynomial.h"

Polynomial::Polynomial()
{
}
Polynomial::Polynomial(Polynomial& copy)
{
std::vector<PolyNumber> copyFrom = copy.bag.toVector();
for (int i = 0; i < copyFrom.size(); i++)
{
bag.add(copyFrom[i]);
}
}
Polynomial::Polynomial(int coeffient[POLYNOMIAL_SIZE], int size)
{
for (int i = 0; i <= size; i++)
{
PolyNumber number = { coeffient[i], i + 1 };
bag.add(number);
}
}
int Polynomial::degree()
{
int max = 0;
std::vector<PolyNumber> result = bag.toVector();
for (int i = 0; i < result.size(); i++)
{
if (result[i].getDegree() > max)
{
max = result[i].getDegree();
}
}
return max;
}
int Polynomial::coefficient(int power)
{
int result = 0;
std::vector<PolyNumber> powerOf = bag.toVector();
for (int i = 0; i < powerOf.size(); i++)
{
if (powerOf[i].getDegree() == power)
{
result = powerOf[i].getCoefficient();
}
}
return result;
}
bool Polynomial::changeCoefficient(int newCoefficient, int power)
{
PolyNumber number = { newCoefficient, power };
int result = coefficient(power) + newCoefficient;
bag.remove(number);
number.setCoefficient(result);
bag.add(number);
return true;
}

Answer 1

您有#include "PolyNumber.cpp"而不是#include "PolyNumber.h"。

这使得PolyNumber.cpp中定义的所有方法都被包括(并重新定义(在Polynomial.cpp中。LinkedBag也是如此。

为什么要包括cpp？