Updating a variable in a struct

November 22, 2021

So I just created a struct that makes a rectangle. the struct itself look likes this

    struct _rect
{
    //bottom left vertex
    int x = 0;
    int y = 0;

    // width and height 
    int width = 0;
    int height = 0;

    //top right vertex
    int y2 = y + height;
    int x2 = x + width; 
};

//init rect
_rect rect01;
rect01.x = rect01.y = 50;
rect01.width = rect01.height = 200;

in the main cpp when I want to create an instance of it I just want to enter bottom left x and y, plus width and height and I want it to calculate top right vertex by itself, is there a way to assign x2 and y2 their values without manuly doing so ?

>Solution :

You should create a specific class:

class Rect
{
public:
  Rect(int x, int y, unsigned int width, unsigned int height)
  : x(x), y(y), width(width), height(height)
  {};

  int x() { return x; };
  int y() { return y; };
  int top() { return y + height; };
  int right() { return x + width; };

private:
  int x;
  int y;
  unsigned int width;
  unsigned int height;
}

That give you the possibility to do the computation you need in the class methods.
You can also create setters and more getters if you want.