namespace Sort
{
 public class School
 {
 public int? Order { get; set; }
 public string Name { get; set; }
 }

 public class Class
 {
 public int? Order { get; set; }
 public string Name { get; set; }
 public School School { get; set; }
 }

 public class Student
 {
 public int? Order { get; set; }
 public string Name { get; set; }
 public Class Class { get; set; }

 }
}

private int CompareInit(int? x, int? y)
 {
  if (x == null && y == null) //如果都是空 那么返回0相等
  return 0;

  if (x.HasValue && y == null) //如果傳入X有值，但是Y是空的，那么X比Y小 返回-1。
  return -1;

  if (x == null && y.HasValue) //如果傳入X為空，但是Y有值，那么X比Y大 返回1。
  return 1;

  if (x.Value > y.Value)
  return 1;

  if (x.Value < y.Value)
  return -1;

  return 0;   //否則兩個(gè)數(shù)相等
 }

public class Student : IComparable<Student>
 {
  public int? Order { get; set; }
  public string Name { get; set; }
  public Class Class { get; set; }
  public int CompareTo(Student other)
  {
   if (ReferenceEquals(this, other)) return 0; //如果兩個(gè)值的引用相同，那么直接返回相等。
   if (ReferenceEquals(null, other)) return 1; //如果該實(shí)例是空的，但是傳入的實(shí)例不是空的，那么返回1
   //比較學(xué)校的序號(hào)
   var compareResult = CompareInit(this.Class.School.Order, other.Class.School.Order);
   if (compareResult != 0) return compareResult;
   //比較班級(jí)的序號(hào)
   compareResult = CompareInit(this.Class.Order, other.Class.Order);
   if (compareResult != 0) return compareResult;
   //比較學(xué)生的學(xué)號(hào)
   compareResult = CompareInit(this.Order, other.Order);
   if (compareResult != 0) return compareResult;
   //如果以上還未區(qū)分出大小，比較學(xué)校的名稱(chēng)
   compareResult = String.CompareOrdinal(this.Class.School.Name, other.Class.School.Name);
   if (compareResult != 0) return compareResult;
   //比較班級(jí)的名稱(chēng)
   compareResult = String.CompareOrdinal(this.Class.Name, other.Class.Name);
   if (compareResult != 0) return compareResult;
   //比較學(xué)生的名稱(chēng)
   return String.CompareOrdinal(this.Name, other.Name);

  }

using System;
using System.Collections.Generic;

namespace Sort
{
 class Program
 {
  static void Main(string[] args)
  {
   var students = InitData();
   students.Sort(); //此處執(zhí)行了Sort方法
   Console.WriteLine("Name-Order");
   foreach (var student in students)
   {
    Console.WriteLine($"學(xué)校:{student.Class.School.Name}-{student.Class.School.Order}>>班級(jí):{student.Class.Name}-{student.Class.Order}>>學(xué)生:{student.Name}-{student.Order}");
   }

   Console.ReadLine();
  }

  static List<Student> InitData() //創(chuàng)建數(shù)據(jù)
  {
   var school1 = new School()
   {
    Order = 1,
    Name = "A",

   };
   var school2 = new School
   {
    Name = "B",
    Order = 0
   };

   var class1 = new Class
   {
    Order = 1,
    Name = "1",
    School = school1,
   };

   var class2 = new Class
   {
    Order = 2,
    Name = "2",
    School = school1,
   };

   var class3 = new Class
   {
    Order = 1,
    Name = "1",
    School = school2,
   };

   var student1 = new Student
   {
    Order = 1,
    Name = "1",
    Class = class1,
   };

   var student2 = new Student
   {
    Order = 2,
    Name = "2",
    Class = class1,
   };

   var student3 = new Student
   {
    Order = 3,
    Name = "3",
    Class = class1,
   };

   var student4 = new Student
   {
    Order = 1,
    Name = "1",
    Class = class2,
   };

   var student5 = new Student
   {
    Order = 1,
    Name = "1",
    Class = class3,
   };
   return new List<Student> { student5, student3, student4, student2, student1 };

  }
 }
}