System IO C# by API

using System;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
class MainClass
{
  [STAThread]
  static void Main(string[] args)
  {
    Point p1 = new Point();
    p1.xpoint = 1;
    p1.ypoint = 2;
    Stream stream = File.Open("point.bin", FileMode.Create);
    BinaryFormatter bformatter = new BinaryFormatter();
    bformatter.Serialize(stream, p1);
    stream.Close();
    Stream openStream = File.Open("point.bin", FileMode.Open);
    Point desierializedPoint = new Point();
    desierializedPoint = (Point)bformatter.Deserialize(openStream);
  }
}
[Serializable()]
class Point
{
  public int xpoint;
  public int ypoint;
}