c++ - 运算符重载函数

Question

我在编译如下所示的运算符( double 值)函数代码时收到一条错误消息。代码只是为了找到一个点到原点的距离。请告诉我我哪里出错了，并告诉我你是如何解决它的。如果您需要更多信息，请告诉我。谢谢!

编译错误消息:

Point.cpp: In member function ‘CS170::Point CS170::Point::operator- 
(double)’:

Point.cpp:187:49: error: no matching function for call to 

‘CS170::Point::Point(double)’

 return Point(sqrt(((x * value) + (y * value))));
                                               ^

驱动文件中用于实现的代码:

pt3 = pt1 - 2;

  Point Point::operator-(double value)
{

    Point temp;
    temp=sqrt(((x * value) + (y * value)));
    return temp ;

}

//list.h文件

 class Point
  {
    public:
     // Constructors (2)
  explicit Point(double x, double y); 

  Point();

   double getX() const;

   double getY() const;

   Point operator+(const Point& other)const ;

   Point& operator+(double value);


   Point operator*(double value) ;

   Point operator%(double angle);


   double operator-(const Point& other)const ;

   Point operator-(double value);

   Point operator^(const Point& other);

   Point operator+=(double value);
   Point& operator+=(const Point& other) ;

   Point& operator++();
   Point operator++(int); 

   Point& operator--(); 
   Point operator--(int); 

   Point& operator-();


        // Overloaded operators (14 member functions)
   friend std::ostream &operator<<( std::ostream &output, const Point 
  &point );
    friend std::istream &operator>>( std::istream  &input, Point 
  &point );

    // Overloaded operators (2 friend functions)

private:
  double x; // The x-coordinate of a Point
  double y; // The y-coordinate of a Point

    // Helper functions
  double DegreesToRadians(double degrees) const;
  double RadiansToDegrees(double radians) const;
   };

 // Point& Add(const Point& other); // Overloaded operators (2 non-member, 
 non-friend functions)
    // Point& Multiply(const Point& other);
    Point operator+( double value, const Point& other );
    Point operator-( double value, const Point& other );

Answer 1

Point 类构造函数有两个参数，x 和 y，而 sqrt 的结果是一个单一的值(value)。如果你想两次使用相同的值，那么要么创建一个接受单个值的构造函数，要么将 sqrt 的结果赋给一个变量，然后将该变量传递给构造函数两次。