C++ 在另一个类的函数中返回一个类，反之亦然，编译错误（递归）

有人能帮我减轻痛苦吗。我试图组织两个类（点），以在它们的方法中返回相反的类。笛卡尔点类具有返回极点的方法，反之亦然

Point2D.h

#pragma once
#include "PointPolar2D.h"
class Point2D
{
private:
    double x;
    double y;

public:
    Point2D(double x, double y);

    PointPolar2D toPolar();

    ~Point2D();
};

#pragma once
#include "Point2D.h"

class PointPolar2D
{
private:
    double radius;
    double angle;

public:
    PointPolar2D(double radius, double angle);

    Point2D toCartesian();

    ~PointPolar2D();
};

Point2D.cpp

#include "stdafx.h"
#include "Point2D.h"
#include "PointPolar2D.h"


Point2D::Point2D(double x, double y) : x(x), y(y)
{
}

PointPolar2D Point2D::toPolar()
{
    return PointPolar2D(1, 4);
}

Point2D::~Point2D()
{
}

#pragma once
#include "Point2D.h"

class PointPolar2D
{
private:
    double radius;
    double angle;

public:
    PointPolar2D(double radius, double angle);

    Point2D toCartesian();

    ~PointPolar2D();
};

PointPolar2D.h

#pragma once
#include "PointPolar2D.h"
class Point2D
{
private:
    double x;
    double y;

public:
    Point2D(double x, double y);

    PointPolar2D toPolar();

    ~Point2D();
};

#pragma once
#include "Point2D.h"

class PointPolar2D
{
private:
    double radius;
    double angle;

public:
    PointPolar2D(double radius, double angle);

    Point2D toCartesian();

    ~PointPolar2D();
};

PointPolar2D.cpp

#include "stdafx.h"
#include "Point2D.h"
#include "PointPolar2D.h"


Point2D::Point2D(double x, double y) : x(x), y(y)
{
}

PointPolar2D Point2D::toPolar()
{
    return PointPolar2D(1, 4);
}

Point2D::~Point2D()
{
}

#pragma once
#include "Point2D.h"

class PointPolar2D
{
private:
    double radius;
    double angle;

public:
    PointPolar2D(double radius, double angle);

    Point2D toCartesian();

    ~PointPolar2D();
};

它不编译。错误为：toPolar:unknown override说明符以及前面的意外标记

请帮我找出原因。这一定是什么明显的或不是。 如果需要，我将提供任何澄清。 谢谢

已编辑

---

按照@Amit的建议创建MCVE。谢谢。

从类的名称来看，我猜

PointPolar2D

是

Point2D

的一个子类

因此，PointPolar2D.h需要

#包括
Point2D.h。你还有：

#include "PointPolar2D.h"

在Point2D.h中。这就是圆形夹杂。它会导致各种各样的问题

从Point2D.h中删除该行并添加一个正向声明

class PointPolar2D;

声明函数不需要完整的类定义

PointPolar2D toPolar();

提前声明就足够了

确保
#在Point2D.cpp中包含
PointPolar2D.h。您需要定义
PointPolar2D
来实现
Point2D:：toPolar
您可能会遇到递归包含的问题：@R即使没有提供解决此问题的所有类。谢谢你抽出时间+1.