用一个类描述一只猫。

public class Cat
...{
 private long _id; // identifier
 private string _name;
 private DateTime _birthdate;
 private Cat _mate;
 private Set _kittens;
 private Color _color;
 private char _sex;
 private float _weight;
 public long Id
 ...{
  get ...{ return _id; }
  set ...{ _id = value; }
 }
 public string Name
 ...{
  get ...{ return _name; }
  set ...{ _name = value; }
 }
 public DateTime Birthdate
 ...{
  get ...{ return _birthdate; }
  set ...{ _birthdate = value; }
 }
 public Cat Mate
 ...{
  get ...{ return _mate; }
  set ...{ _mate = value; }
 }
 public Set Kittens
 ...{
  get ...{ return _kittens; }
  set ...{ _kittens = value; }
 }
 public Color Color
 ...{
  get ...{ return _color; }
  set ...{ _color = value; }
 }
 public char Sex
 ...{
  get ...{ return _sex; }
  set ...{ _sex = value; }
 }
 public float Weight
 ...{
  get ...{ return _weight; }
  set ...{ _weight = value; }
 }
}