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 };

 }
 }
}