C++ 某些文件应该放在哪里#include'；这些课程有哪些课程？

我在上弧度课和学位课。每个类都有一个构造函数，它将另一种类型的对象作为参数，进行度/弧度转换，并用结果初始化度或弧度参数，如下所示

Class Radian
{
    private:
      double radians;
    public:
      // ......
      Radian(Degree d) {
      radians = d.getDegrees() * (pi / 180);
      }
      // ...

---

学位课程也是同样的方式，但有可能。因此，为了确保没有某种链接错误，每个标题是否应该包含另一个？他们各自的cpp呢？我需要转发类声明吗？

在这种情况下，您应该使用转发声明。

您需要做三件事（可能是四件事）：

• 使用包括防护装置-

  #如果没有弧度…

• 使用前向声明，即

  类度

• 将构造函数主体从头文件移出并移到.cpp文件中。这是因为类的前向声明不允许引用成员，如

  getDegrees（）

• 理想情况下，让构造函数接受

  const&

  参数

---

因为它们紧密地联系在一起，所以它们可能属于一个文件。这使得编写两个内联构造函数成为可能：

class radian;

class degree {
public:
    degree(radian r);
private:
    double degrees;
};


class radian {
public:
    radian(degree d);
private:
    double radians;
};

inline degree::degree(radian r) : degrees(r.get_radians() * 180 / pi) { }
inline radian::radian(degree d) : radians(d.get_degrees() * pi / 180) { }

---

我可能会这样做：
前进.hpp

#pragma once
class Radian;
class Degree;

#pragma once
#include "forward.hpp"

class Radian {
    public:
        Radian(Degree d);

    private:
        double radians;
};

#include "radian.hpp"
#include "degree.hpp"

Radian::Radian(Degree d) {
    radians = d.getDegrees() * (pi / 180);
}

#pragma once
#include "forward.hpp"

class Degree {
    public:
        Degree(double x);
        double getDegrees() const;
    private:
        double deg;
}

#include "degree.hpp"

Degree::Degree(double x) {
    deg = x;
}

double Degree::getDegrees() const {
    return deg;
}

弧度hpp

#pragma once
class Radian;
class Degree;

#pragma once
#include "forward.hpp"

class Radian {
    public:
        Radian(Degree d);

    private:
        double radians;
};

#include "radian.hpp"
#include "degree.hpp"

Radian::Radian(Degree d) {
    radians = d.getDegrees() * (pi / 180);
}

#pragma once
#include "forward.hpp"

class Degree {
    public:
        Degree(double x);
        double getDegrees() const;
    private:
        double deg;
}

#include "degree.hpp"

Degree::Degree(double x) {
    deg = x;
}

double Degree::getDegrees() const {
    return deg;
}

弧度cpp

#pragma once
class Radian;
class Degree;

#pragma once
#include "forward.hpp"

class Radian {
    public:
        Radian(Degree d);

    private:
        double radians;
};

#include "radian.hpp"
#include "degree.hpp"

Radian::Radian(Degree d) {
    radians = d.getDegrees() * (pi / 180);
}

#pragma once
#include "forward.hpp"

class Degree {
    public:
        Degree(double x);
        double getDegrees() const;
    private:
        double deg;
}

#include "degree.hpp"

Degree::Degree(double x) {
    deg = x;
}

double Degree::getDegrees() const {
    return deg;
}

度hpp

#pragma once
class Radian;
class Degree;

#pragma once
#include "forward.hpp"

class Radian {
    public:
        Radian(Degree d);

    private:
        double radians;
};

#include "radian.hpp"
#include "degree.hpp"

Radian::Radian(Degree d) {
    radians = d.getDegrees() * (pi / 180);
}

#pragma once
#include "forward.hpp"

class Degree {
    public:
        Degree(double x);
        double getDegrees() const;
    private:
        double deg;
}

#include "degree.hpp"

Degree::Degree(double x) {
    deg = x;
}

double Degree::getDegrees() const {
    return deg;
}

degree.cpp

#pragma once
class Radian;
class Degree;

#pragma once
#include "forward.hpp"

class Radian {
    public:
        Radian(Degree d);

    private:
        double radians;
};

#include "radian.hpp"
#include "degree.hpp"

Radian::Radian(Degree d) {
    radians = d.getDegrees() * (pi / 180);
}

#pragma once
#include "forward.hpp"

class Degree {
    public:
        Degree(double x);
        double getDegrees() const;
    private:
        double deg;
}

#include "degree.hpp"

Degree::Degree(double x) {
    deg = x;
}

double Degree::getDegrees() const {
    return deg;
}

---

他不能。弧度构造函数（如所写）无法编译。我在再次阅读后注意到了这一点，并标记了答案。很抱歉最好是修复答案而不是标记。@iccthedral他需要两者，还需要将引用另一个类的至少一个类成员函数的实现移动到.cpp文件中。