1 using System;
 2 
 3 namespace ConsoleApp1
 4 {
 5     class Program
 6     {
 7         static void Main(string[] args)
 8         {
 9 
10             {
11                 Student student = new Student("蛋蛋", "张");
12 
13                 Console.WriteLine(student.ToString());
14 
15                 student.Show();
16             }
17 
18             {
19                 //条件运算符
20                 Student student1 = null;
21 
22                 //1. 得到的结果一定要支持null
23                 //2. 如果 student1 是 null，返回 null，如果 student1 有值 就返回 student1.FirstName
24                 string fullName = student1?.FirstName;
25 
26                 //必须为可空类型，如果是  int id = student1?.Id; 则报错
27                 int? id = student1?.Id;
28 
29                 Console.WriteLine("Hello World!");
30 
31                 student1 = new Student("AA", "BB");
32                 fullName = student1?.FullName1;
33 
34                 //1. 判断student1是否为null，如果为null，直接返回null；
35                 //2. 如果不为null，判断 student1.FullName1 是否为null，如果为null，返回“张三”，如果不为null，返回 student1.FullName1
36                 string testName = student1?.TestName ?? "张三";
37             }
38 
39             //字符串内插
40             {
41                 string firstName = "蛋蛋";
42                 string lastName = "张";
43                 string strs = $"{{{lastName}}}-{firstName}"; //结果：{张}-蛋蛋
44             }
45 
46             //异常筛选器
47             {
48                 try
49                 {
50                     throw new Exception("我是张蛋蛋的好朋友!");
51                 }catch(Exception ex) when(ex.Message.Contains("张蛋蛋"))
52                 {
53                     Console.WriteLine("如果异常Message字符串中包含‘张蛋蛋’，那么就会显示此段话！");
54                     //throw;
55                 }
56             }
57             //nameof 表达式
58             {
59 
60                 string className = nameof(Student);
61                 Console.WriteLine($"获取到类名称：{className}");
62             }
63 
64         }
65     }
66 }

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Text;
 4 
 5 namespace ConsoleApp1
 6 {
 7    public class Student
 8     {
 9         public Student(string firstName,string lastName)
10         {
11             FirstName = firstName;
12             LastName = lastName;
13         }
14 
15         public int? Id { get; set; }
16         public string TestName { get; set; }
17 
18         /// <summary>
19         /// 只能通过构造函数赋值
20         /// </summary>
21         public string FirstName { get; }
22         public string LastName { get; }
23 
24         /// <summary>
25         /// FullName1 与 FullName2 功能相同
26         /// </summary>
27         public string FullName1
28         {
29             get
30             {
31                 return string.Format("{0}-{1}", this.FirstName, this.LastName);
32             }
33         }
34 
35         public string FullName2=> string.Format("{0}-{1}", this.FirstName, this.LastName);//念 goes to
36 
37         public void Show()
38         {
39             Console.WriteLine(string.Format("FullName1:{0}",FullName1));
40             Console.WriteLine(string.Format("FullName2:{0}", FullName2));
41         }
42 
43         /// <summary>
44         /// 方法A （方法A与方法B功能相同）
45         /// </summary>
46         /// <returns></returns>
47         public override string ToString() => string.Format("我是方法：{0}-{1}", this.FirstName, this.LastName);//念 goes to
48         /// <summary>
49         /// 方法B
50         /// </summary>
51         /// <returns></returns>
52         //public override string ToString()
53         //{
54         //    return string.Format("我是方法：{0}-{1}", this.FirstName, this.LastName);
55         //}
56 
57     }
58 }