Updating a variable in a struct-CodePudding

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 ?

CodePudding user response：

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.

CodePudding user response：

Below is the complete working example:

#include <iostream>
class Rect
{
public:
  //parameterized constructor 
  Rect(int px, int py, unsigned int pwidth, unsigned int pheight): x(px), y(py), width(pwidth), height(pheight), x2(x   width), y2(y   height)
  {
    
    
   
  };
  
  //getter so that we can get the value of x2 
  int getX2()
  {
      return x2;
  }
  //getter so that we can get the value of y2 
  int getY2()
  {
      return y2;
  }

private:
  int x = 0;
  int y = 0;
  unsigned int width = 0;
  unsigned int height = 0;
  
  int x2 = 0, y2 = 0;
};

int main()
{
    //create Rect instance
    Rect r(50, 50, 200, 200);
    //lets check if x2 and y2 were calculate correctly
    std::cout<<"x2 is: "<< r.getX2()<<std::endl;
    std::cout<<"y2 is: "<< r.getY2()<<std::endl;
}

The output of the above program can be seen here.