矩形

using System;
class Rectangle
{
 private float length=1.0f;
 private float width=1.0f;

 public float SetLength(float length)
 {
  this.length=length;
  if((length<0.0f)||(length>2.0f))
  {
   Console.WriteLine ("长的取值范围应在1.0-2.0之内，请重新设值。");
   return 0.0f;
  }
  return width;
 }
 public float SetWidth(float width)
 {
        this.width=width;
  if((width<0.0f)||(width>2.0f))
  {
   Console.WriteLine ("宽的取值范围应在1.0-2.0之内，请重新设值。"); 
   return 0.0f;
  }
  return width;
 }
 public float GetLength(float length)
 {
  return length;
 }
 public float GetWidth(float width)
 {
  return width; 
 }
 public float perimeter()
 {
  return length*2+width*2;
 }
 public float area()
 {
    return length*width;
 }

}
class Rectangle_Test
{
 public static void Main()
 {
  Rectangle r1=new Rectangle ();
  r1.SetLength (1.8f);
  r1.SetWidth (1.2f);
     Console.WriteLine (r1.perimeter ());
  Console.WriteLine (r1.area ());

 }

}