public class Person { public DateTime birth; public DateTime? death; string name; public TimeSpan Age { get { if (!death.HasValue) { return DateTime.Now - birth; } else { return death.Value - birth; } } } //构造函数 public Person(string name, DateTime birth,DateTime?death) { this.birth = birth; this.death = death; this.name = name; } } Person tr = new Person("AAAA", new DateTime(1988, 12, 13),null); Person kk = new Person("BBBB", new DateTime(1912, 12, 13), new DateTime(1954, 12, 12)); Console.ReadKey();