Question

我有一个班级Point和Vector Vector继承自Point，Point使用Vector作为朋友我有一个cpp文件..我怎么解决这个冲突。我不想使用头文件我的代码是：

 class Vector:Point
 {
  //something
 };

 class Point
 {
 public:
     friend class Vector;

     double x;
     double y;
     Vector Point::operator-( Point Q)        // Vector diff of Points
     {
         Vector v;
         v.x = x - Q.x;
         v.y = y - Q.y;
         v.z = z - Q.z;
         v.dimn = max( dimn, Q.dim());
         return v;
     }

     Point Point::operator+( Vector v)        // +ve translation
     {
         Point P;
         P.x = x + v.x;
         P.y = y + v.y;
         P.z = z + v.z;
         P.dimn = max( dimn, v.dim());
         return P;
     }

     Point Point::operator-( Vector v)        // -ve translation
     {
         Point P;
         P.x = x - v.x;
         P.y = y - v.y;
         P.z = z - v.z;
         P.dimn = max( dimn, v.dim());
         return P;
     }

     Point& Point::operator+=( Vector v)        // +ve translation
     {
         x += v.x;
         y += v.y;
         z += v.z;
         dimn = max( dimn, v.dim());
         return *this;
     }

     Point& Point::operator-=( Vector v)        // -ve translation
     {
         x -= v.x;
         y -= v.y;
         z -= v.z;
         dimn = max( dimn, v.dim());
         return *this;
     }
};

Answer 1

尝试前瞻声明 -

class Vector;
class Point { ... }

Answer 2

尝试像这样声明Point类：

class Point;

class Vector : Point
{ /* your code here */ };

class Point
{ /* your code here */ };

Answer 3

在第一次使用点之前添加“前向声明”：

class Point;

这就是全部。它说有一个类Point将在稍后声明。

声明类和继承时发生冲突

3 个答案: