比较和排序：IComparable和IComparer

class Person : IComparable
{
     public string Name { get; set; }

     public int Age { get; set; }

     public override string ToString()
     {
          return string.Format("Name : {0} ; Age : {1} .", this.Name, this.Age);
     }

     public int CompareTo(object obj)
     {
           Person p = obj as Person;
           return this.Age.CompareTo(p.Age);
     }
}
static void Main(string[] args)
{

     List<Person> persons = new List<Person>();
     persons.Add(new Person() { Name = "ALin", Age = 13 });
     persons.Add(new Person() { Name = "John", Age = 34 });
     persons.Add(new Person() { Name = "Lee", Age = 26 });
     persons.Add(new Person() { Name = "Kui", Age = 47 });
     persons.Add(new Person() { Name = "Meimei", Age = 45 });

     persons.Sort();

     foreach (Person item in persons)
     {
          Console.WriteLine(item.ToString());
     }

     Console.ReadKey();
}

class SortByName : IComparer<Person>
{
      public int Compare(Person x, Person y)
      {
           return x.Name.CompareTo(y.Name);
      }
}  

persons.Sort(new SortByName());