格式化错误

using System;
using System.Windows.Forms;
public class Test
{
  static void Main()
  {
  Rectangle rec1 = new Rectangle(10, 20, 100, 50);
  string output = "rec1:";
  output += rec1.Print();
  rec1.Inflate(20, 20);
  output += "rec1Inflate:";
  output += rec1.Print();
  MessageBox.Show(output, "输出结果");
  }
}
//
public class Rectangle
{
  private int x;
  private int y;
  private int width = 10;
  private int height = 20;
  public Rectangle(int myx, int myy, int mywidth, int myheight)
  {
  x = myx;
  y = myy;
  width = mywidth;
  height = myheight;
  }
  public int X
  {
  set { x = value; }
  get { return x; }
  }
  public int Y
  {
  set { y = value; }
  get { return y; }
  }
  public int Height
  {
  set
  {
  if (value > 0)
  height = value;
  }
  get { return height; }
  }
  public int Width
  {
  set
  {
  if (value > 0)
  width = value;
  }
  get { return width; }
  }
  public int Area
  {
  get { return width * height; }
  }
  public void Inflate(int inwidth, int inheight)
  {
  X = X - inwidth;
  Y = Y - inheight;
  Height = Height + 2 * inheight;
  Width = width + 2 * inwidth;
  }
  public string Print()
  {
  string str = string.Format("X={0},Y={1}.",X,Y)+"\n";
  str += string.Format("Width={0],Height={1}.", Width, Height) + "\n";
  str += string.Format("Area={0}", Area) + "\n";
  return str;
  }
}

没看出有啥错误啊，能否把你错误标出来？

你拷贝到程序里一运行就知了、

你拷进去运行就知道了、