我是这样行的:

public string GetValue(string name)
            {
                return name switch
                {
                    var x when name is "test1" || name is "test2" => "finch",
                    "test2" => somevalue,
                    _ => name
                };
            }

c# 9支持以下功能:

var switchValue = 3;
var resultText = switchValue switch
{
    1 or 2 or 3 => "one, two, or three",
    4 => "four",
    5 => "five",
    _ => "unknown",
};

另外:

var switchValue = 3;
var resultText = switchValue switch
{
    >= 1 and <= 3 => "one, two, or three",
    4 => "four",
    5 => "five",
    _ => "unknown",
};

源

对于旧版本的c#，我使用以下扩展方法:

public static bool In<T>(this T val, params T[] vals) => vals.Contains(val);

是这样的:

var switchValue = 3;
var resultText = switchValue switch
{
    var x when x.In(1, 2, 3) => "one, two, or three",
    4 => "four",
    5 => "five",
    _ => "unknown",
};

它比x == 1 || x == 2 || x == 3更简洁，并且比new [] {1,2,3}. contains (x)的顺序更自然。

我设法安装了它，但我还没有找到一种方法，可以用新语法为单个开关部分指定多个单独的大小写标签。

但是，你可以创建一个新变量来捕获值，然后使用一个条件来表示应该有相同结果的情况:

var resultText = switchValue switch
{
    var x when
        x == 1 ||
        x == 2 ||
        x == 3 => "one to three",
    4 => "four",
    5 => "five",
    _ => "unknown",
};

如果你有很多用例要测试，这实际上更简洁，因为你可以在一行中测试一系列值:

var resultText = switchValue switch
{
    var x when x > 0 && x < 4 => "one to three",
    4 => "four",
    5 => "five",
    _ => "unknown",
};

如果你仍然在使用c# 8，所以不能像上面的答案一样使用c# 9 1或2或3 =>方法，你也可以用一种方式来避免创建额外的变量x，与接受的答案中的switchValue值相同(当然这是完全正确的，我只是建议一个替代方案，因为我不喜欢额外的x)。

var list = new List<int> { 3, 4, 5 };

var resultText = switchValue switch
{
    1 => "one",
    2 => "two",
    _ when list.Contains(switchValue) => "three to five",
    _ => "unknown",
};

显然，你可以用任意值替换_ when后面的条件，比如switchValue == 3 || switchValue == 4 || switchValue == 5;答案的重点是显示_ when位。

我只是认为_ when =>表示“其他时候”，_ =>表示“其他”。

我是这样行的:

public string GetValue(string name)
            {
                return name switch
                {
                    var x when name is "test1" || name is "test2" => "finch",
                    "test2" => somevalue,
                    _ => name
                };
            }

如果您的交换机类型是标志enum

[System.Flags]
public enum Values 
{
    One = 1, 
    Two = 2, 
    Three = 4,
    Four = 8,
    OneToThree = One | Two | Three
}

var resultText = switchValue switch
{
    var x when Values.OneToThree.HasFlag(x) => "one to three",
    Values.Four => "4",
    _ => "unknown",
};