c++ - I don’t know where the error is, and I don’t know how to correct it.

Question

Code:

include "stdafx.h"
#include<iostream>
#include<string>
#include<cmath>
#include<sstream>
using namespace std;
#define PI 3.141592653
class VecPosition
{
public:
    VecPosition(double  vx = 0,double  vy = 0);

    VecPosition        operator --            ();
    VecPosition        operator +             (const double      &d);
    VecPosition        operator +             (const VecPosition &p);
    VecPosition        operator -             (const double      &d);
    VecPosition        operator -             (const VecPosition &p);
    VecPosition        operator *             (const double      &d);
    VecPosition        operator *             (const VecPosition &p);
    VecPosition        operator /             (const double      &d);
    VecPosition        operator /             (const VecPosition &p);
    void               operator =             (const double      &d);
    void               operator +=            (const VecPosition &p);
    void               operator +=            (const double      &d);
    void               operator -=            (const VecPosition &p);
    void               operator -=            (const double      &d);
    void               operator *=            (const VecPosition &p);
    void               operator *=            (const double      &d);
    void               operator /=            (const VecPosition &p);
    void               operator /=            (const double      &d);
    bool               operator !=            (const VecPosition &p);
    bool               operator !=            (const double      &d);
    bool               operator ==            (const VecPosition &p);
    bool               operator ==            (const double      &d);


    void               draw(); // 绘制到屏幕
    string             str(double dX, double dY);// 将向量坐标转为字符串，格式为“(x=, y=)”
    
    bool     setX(double  dX)
    {
        return false;
    }
    double   getX() const
    {
        return m_x;
    }
    bool     setY(double  dY)
    {
        return false;
    }
    double   getY() const
    {
        return m_y;
    }

    

    void   setVecPosition(double dX=0 ,double dY=0 );
    double getDistanceTo(const VecPosition p)
    {
        return sqrt((p.m_x-p.m_x)*(p.m_x-p.m_x) + (p.m_y-p.m_y)*(p.m_y - p.m_y));
    }//获得两点间的距离
    VecPosition  setMagnitude(double d) 
    {
        m_x = d*cos(this->getDirection());
        m_y = d*sin(this->getDirection());
        return *this;

    }//设置向量长度为d
    double getMagnitude(double d) const
    {
        return sqrt((m_x)*(m_x) + (m_y)*(m_y));
    }//获取向量长度
    double getDirection() const 
    {
        double a[4] = { 0, 0, 1, 0 };

        double b[4] = {0,0,m_x,m_y };

        double t;
        double angle;


        t = ((a[0] - a[2])*(b[0] - b[2]) + (a[1] - a[3])*(b[1] - b[3])) / (sqrt(pow(a[0] - a[2], 2) + pow(a[1] - a[3], 2))*sqrt(pow(b[0] - b[2], 2) + pow(b[1] - b[3], 2)));
        cout << "这两个向量的夹角为:" << acos(t)*(180 / PI) << "度" << endl;

        return angle= acos(t)*(180 / PI);
    }//获取向量方向（与X轴夹角）

                                            
    bool   isBetweenX(const VecPosition &p1, const VecPosition &p2)
    {
        return false;
    }
    bool   isBetweenX(const double  &d1, const double &d2)
    {
        return false;
    }
    bool   isBetweenY(const VecPosition &p1, const VecPosition &p2)
    {
        return false;
    }
    bool   isBetweenY(const double &d1, const double &d2)
    {
        return false;
    } // 判断坐标是否在给定两点的X，Y之间

    
    VecPosition  normalize()

    {
        return  VecPosition(cos(this->getDirection()), sin(this->getDirection()));
    }// 正规化坐标
    
    VecPosition  rotate(double angle)
        {
            angle = angle / 180 * PI;   //由于输进去的角度值不是幅度制，统一化成幅度值
            angle += this->getDirection();
            return VecPosition(this->getMagnitude(m_x)*cos(angle), this->getMagnitude(m_y)*sin(angle));
        }// 向量旋转

    
    static VecPosition getVecPositionFromPolar(double dMag, double ang)
    {
        ang = ang / 180 * PI;             
        return VecPosition(dMag*cos(ang), dMag*sin(ang));


    }// 根据极坐标获取笛卡尔坐标
    
    static double  normalizeAngle(double angle)
    {
        angle = angle / PI * 180;//化成幅度值
        int a = int(angle / 180);
        if (a % 2 == 0)
            return angle - a * 180;
        else
            return angle - (a + 1) * 180;

    }// 将任意角度转为（－180，180]范围

private:
    double m_x;
    double m_y;
    string a;
    
    
};
VecPosition::string str(double dX, double dY) {
    ostringstream stream;
    cout << "(x=" << dX << ", y=" << dY << ")";
    return stream.str();
}

Answer 1

Write VecPosition::string str(double dX, double dY) as string VecPosition::str(double dX, double dY) Try it

Answer 2

I agree with you upstairs. str is the member function of VecPosition.