A Few Ways of Pattern Matching with C#
This is mostly a post for future me for when I forget how I used pattern matching.
In a previous post, I used pattern matching with a WhenAny of different types of task, so I started playing around more with pattern matching and found at least three ways to use them for my scenario - in an if/else, a switch with a return, and a switch in an expression body.
1public class Program
2{
3 public static async Task Main()
4 {
5 Console.WriteLine(WithAnIfElse<string>("abc"));
6 Console.WriteLine(WithAnIfElse<int>(123));
7
8 Console.WriteLine(WithASwitchAndReturn<string>("abc"));
9 Console.WriteLine(WithASwitchAndReturn<int>(123));
10
11 Console.WriteLine(WithASwitchAndExpressionBody<string>("abc"));
12 Console.WriteLine(WithASwitchAndExpressionBody<int>(123));
13
14 }
15 public static string WithAnIfElse<T>(T item)
16 {
17 if (item is int intValue)
18 {
19 return $"It's a number: {intValue}";
20 }
21 else if (item is string stringValue)
22 {
23 return $"It's a string: {stringValue}";
24 }
25 return "";
26 }
27
28 public static string WithASwitchAndReturn<T>(T item)
29 {
30 string value = item switch
31 {
32 int => $"It's a number: {item.ToString()}",
33 string => $"It's a string: {item as string}",
34 _ => ""
35 };
36 return value;
37 }
38
39 public static string WithASwitchAndExpressionBody<T>(T item) =>
40 item switch
41 {
42 int => $"It's a number: {item.ToString()}",
43 string => $"It's a string: {item as string}",
44 };
45}