小编use*_*527的帖子

我正在研究实现GIS中使用的一套点类型,它们是2D(xy),3D(xyz或xym)或4D(xyzm).M坐标是度量坐标,其他坐标应该是显而易见的.不过,我似乎无法弄清楚如何使PointZM类股x和y从成员Point类.这是我的代码:

#include <iostream>

class Point {
  public:
    double x, y;
    Point (double xNew, double yNew) : x(xNew), y(yNew) {};
};

class PointZ : public Point {
  public:
    double z;
    PointZ (double xNew, double yNew, double zNew) :
        Point(xNew, yNew), z(zNew) {};
};

class PointM : public Point {
  public:
    double m;
    PointM (double xNew, double yNew, double mNew) :
        Point(xNew, yNew), m(mNew) {};
};

class PointZM : public PointZ, public PointM { …