3 Data members

Let us start with a simple class defintion:

class Pixel
{
  public:
    int x, y; // coordinate
};

For now, let us not worry about the public: part. This definition means that all objects of Pixel type has two data members (also known as fields): x and y.

Using this definition, we can proceed to create objects of this Pixel class, as follows:

Pixel dotA, dotB;

We can access individual data member using the dot notation. For example, we can use the following code to initialize a pixel to the origin of a screen:

dotA.x = dotA.y = 0;

We can also write a subroutine to reset a pixel to the origin:

void pixelReset(Pixel &p)
{
  p.x = p.y = 0;
}

So far, everything that we have done can be done with a struct definition. We can add additional subroutines that deal with pixels. For example:

• pixelDraw: a subroutine to draw a pixel
• pixelErase: a subroutine to erase a pixel