Linq Orderby null,string.Empty, 指定字符

using System;
using System.Collections.Generic;
using System.Linq;

public class Program
{
  public static void Main()
  {
    var strL = new List<string>{"4",  "2", null, "3", "1"};
    Console.WriteLine("*********null**to the end*********");
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e is null ? 1 : 0)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e is null ? 1 : 0).ThenBy(e => e)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e is null ? 1 : 0).ThenByDescending(e => e)));
    Console.WriteLine("*********null**to the start***********");
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e is null ? 0 : 1)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e is null ? 0 : 1).ThenBy(e => e)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e is null ? 0 : 1).ThenByDescending(e => e)));
    Console.WriteLine("*********string.Empty**to the end***********");
    strL = new List<string>{"4",  "2", "", "3", "1"};
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e == string.Empty ? 1 : 0)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e == string.Empty ? 1 : 0).ThenBy(e => e)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e == string.Empty ? 1 : 0).ThenByDescending(e => e)));
    Console.WriteLine("*********Specify Characters**to the end***********");
    strL = new List<string>{"4",  "2", "%", "3", "1"};
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e == "%" ? 1 : 0)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e == "%" ? 1 : 0).ThenBy(e => e)));
    Console.WriteLine(string.Join("-", strL.OrderBy(e => e == "%" ? 1 : 0).ThenByDescending(e => e)));

  }

}