IComparer 与 IComparable

         static void Main()
         {
             var people = new ArrayList();
             people.AddRange(new ArrayList
             {
                 new Person{ Name = "Jone",Age = },
                 new Person{ Name = "Tom",Age = },
                 new Person{ Name = "Lily",Age = },
                 new Person {Name = "July",Age =  }
             });
             Console.WriteLine("↓↓↓   Old   ↓↓↓");
             foreach (Person person in people)
             {
                 Console.WriteLine($"person name:{person.Name} age:{person.Age}");
             }
             people.Sort(); //new PersonComparer()
             Console.WriteLine("↓↓↓   New   ↓↓↓");
             foreach (Person person in people)
             {
                 Console.WriteLine($"person name:{person.Name} age:{person.Age}");
             }

             Console.ReadKey();
         }

IComparable 是用于类对其的CompareTo方法进行实现，比较的对象包含自身，并且集合调用默认的Sort方法 （个人理解是框架提供的默认比较方式）

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

         public int Age { get; set; }
         public int CompareTo(object obj)
         {
             if (obj is Person person)
             {
                 return this.Age - person.Age;
             }
             else
             {
                 throw new ArgumentException("Object is not a Person");
             }
         }
     }

IComparer  是比较两个Object，是以比较器的形式存在的，并且集合调用Sort(new XxxComparer())方法（个人理解是框架对默认比较方式的扩展吧，用以满足特定的需求）

 class PersonComparer:IComparer
     {
         public int Compare(object x, object y)
         {
             if (x is Person personX && y is Person personY)
             {
                 if (Object.ReferenceEquals(x,y))
                 {
                     return ;
                 }
                 int result = String.Compare(personX.Name, personY.Name, StringComparison.Ordinal);
                 if (result == )
                 {
                     result = personX.Age - personY.Age;
                 }

                 return result;
             }
             else
             {
                 throw new ArgumentException("Object is not a Person");
             }
         }
     }