如何在switch表达式上忽略一个元组类型？

Question

我有以下开关表达式：

  public Size GetSize(string brand, string isGift) => (brand, isGift) switch
    {
        (brand: "1", isGift: "Y") => Size.Small,
        (brand: "1", isGift: "N") => Size.Medium,
        (brand: "2") => Size.Big, // in this line I get and error 
        _ => Size.NoSize
    };

所以，我知道如果商标是"2“，它将总是Size.Big，我想忽略这条语句中的isGift字符串，但我得到了一个编译错误。有没有办法解决这个问题？

Answer 1

您可以只使用下划线：

public Size GetSize(string brand, string isGift) => (brand, isGift) switch
{
    (brand: "1", isGift: "Y") => Size.Small,
    (brand: "1", isGift: "N") => Size.Medium,
    (brand: "2", _) => Size.Big,
    _ => Size.NoSize
};