C# 重写IComparer 接口

首先定义比较类 继承自IComparer<Racer>

 public class RacerComparer : IComparer<Racer>
     {
         public enum CompareType
         {
             FirstName, LastName, Country, Wins
         }
         private CompareType compareType;
         public RacerComparer(CompareType compareType)
         {
             this.compareType = compareType;
         }
         public int Compare(Racer x, Racer y)
         {
             if (x == null && y == null) return ;
             if (x == null) return -;
             if (y == null) return ;

             int result;
             switch (compareType)
             {
                 case CompareType.FirstName:
                     return string.Compare(x.FirstName, y.FirstName);
                 case CompareType.LastName:
                     return string.Compare(x.LastName, y.LastName);
                 case CompareType.Country:
                     result = string.Compare(x.Country, y.Country);
                     if (result == )
                         return string.Compare(x.LastName, y.LastName);
                     else
                         return result;
                 case CompareType.Wins:
                     return x.Wins.CompareTo(y.Wins);
                 default:
                     throw new ArgumentException("Invalid Compare Type");
             }
         }
     }

 class Racer : IComparable<Racer>
     {
         public int Id { get; private set; }
         public string FirstName { get; set; }
         public string LastName { get; set; }
         public string Country { get; set; }
         public int Wins { get; set; }
         public override string ToString()
         {
             return String.Format("{0} {1}", FirstName, LastName);
         }
         public Racer(int id, string firstName, string lastName, string country)
             : this(id, firstName, lastName, country, wins: )
         {
         }
         public Racer(int id, string firstName, string lastName, string country, int wins)
         {
             this.Id = id;
             this.FirstName = firstName;
             this.LastName = lastName;
             this.Country = country;
             this.Wins = wins;
         }
         public int CompareTo(Racer other)
         {
             if (other == null) return -;
             int compare = string.Compare(this.LastName, other.LastName);
             if (compare == )
                 return string.Compare(this.FirstName, other.FirstName);
             return compare;
         }
     }

调用比较方法

  var graham = new Racer(, "Graham", "Hill", "UK", );
             var emerson = new Racer(, "Emerson", "Fittipaldi", "Brazil", );
             var mario = new Racer(, "Mario", "Andretti", "USA", );

             var racers = new List<Racer>() { graham, emerson, mario };
  racers.Sort(new RacerComparer(RacerComparer.CompareType.Country));