How to get a reference in a struct of the same struct in my code

Question

I have this struct, but I get some errors when I mention a reference to its own type:

struct Point  {
              int x;
              int y;

              bool isLattice;

              Vect2D gradient;

              ///used only when isLattice is false
              Point p00; ///top-left corner
              Point p01; ///top-right corner
              Point p10; ///bottom-left corner
              Point p11; ///bottom-right corner

              ///the displacement vectors  Gradient-this.Vect2D
              Vect2D disp00;
              Vect2D disp01;
              Vect2D disp10;
              Vect2D disp11;  ///used along the gradient vector of the lattice points

              ///the Q-s for each corner Q= Disp*G which are going to be used for the interpolation
              double q00;
              double q01;
              double g10;
              double q11;

          };

I need to know how I should initialize this struct, because this is how I used to do it in the past in other codes. What is the error in this one?

Answer 1

I would guess you're coming from a managed language

struct Point  {
    //...
    Point p00; 
    // ...
}

This is your problem. Objects in C++ are NOT references. This puts an instance of Point inside an instance of Point. How will that work? You could use a pointer, or a reference.

Change

Point p00;

to

Point & p00; // this requires being initialized  
             // in the constructor initialization list

or maybe

std::shared_ptr<Point> p00;

Answer 2

Change Point pX; to Point * pX; .

This way, the code will compile, and you get to initialise the Point pointers using an appropriate constructor.

Answer 3

为什么不在 Point 实例中使用另一种类型的结构？