C# 8.0 新增功能 —模式匹配增强功能—元组模式

一些算法依赖于多个输入。 使用元组模式，可根据表示为​​元组​​的多个值进行切换 。

注意在使用switch时，switch里面用的是小括号(),属性模式用的是大括号{}。

以下根据星期和天气判断今天状态如何：

using System;
using System.Collections.Generic;
using System.Text;

namespace BasicKnowledgeTest
{
    public class Week
    {
        public Weekday Name { get; set; }
        public string Weather { get; set; }

    }

    public static class TestTubeMode
    {
        // 根据星期和天气判断今天状态如何
        public static string GetStatusByWeekday(Week day) =>
        (day.Name, day.Weather) switch
        {
            (Weekday.Sun,"Sunny")=> "today is good",
            (Weekday.Sat, "Sunny")=> "today is very good",
            (Weekday.Mon, "Sunny")=> "today is not  good",
            (Weekday.Sun, "Rainy")=> "today is not good",
            _ => throw new ArgumentException(message: "invalid enum value"),
        };
    }
}

测试

using System;
using System.Diagnostics;

namespace BasicKnowledgeTest
{
    class Program
    {
        static void Main(string[] args)
        {
            var result = TestTubeMode.GetStatusByWeekday(new Week(){Name=Weekday.Sun, Weather= "Sunny" });
            Console.WriteLine(result);
            Console.ReadLine();
        }
    }
}

测试结果

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