How can I find out the number of elements in a class (maybe I didn't describe it that way)?

Question

C++ / C#

Hello. It is necessary to store the X,Y coordinate. I made a class like this:

class posBoll
        {
            public int XposBollX;
            public int XposBollY;
            public posBoll(int X, int  Y)
            {
                this.XposBollX = X;
                this.XposBollY = Y;
            }
        }

I enter the data:

List<posBoll> posBoll = new List<posBoll>();
posBoll xy;
......
xy = new posBoll(i, j); posBoll.Add(xy);

I can get values:

textBox1.Text = posBoll[0].XposBollX.ToString() + " " + posBoll[0].XposBollY.ToString();
               textBox1.Text += " " + posBoll[1].XposBollX.ToString() + " " + posBoll[1].XposBollY.ToString();

The values ​​are stored, but now I know that there are 4 of them. But how to find out the number of all data ??? posBoll.count() - doesn't work (((. Maybe you should use the structure at all)

THANK YOU