如何在C＃中获取下一个（或上一个）枚举值

问题描述

我有一个这样定义的枚举：

I have an enum which is defined like this:

public enum eRat { A = 0, B=3, C=5, D=8 };

因此给定值 eRat.B ，我想要得到下一个是 eRat.C

So given value eRat.B, I want to get the next one which is eRat.C

我看到的解决方案是（不进行范围检查）

The solution I see is (without range checking)

Array a = Enum.GetValues(typeof(eRat));
int i=0 ;
for (i = 0; i < a.GetLength(); i++)
{
       if (a.GetValue(i) == eRat.B)
            break;
}
return (eRat)a.GetValue(i+1):

现在，对于这么简单的事情来说，这太复杂了。您知道更好的解决方案吗？像 eRat.B + 1 或 Enum.Next（Erat.B）之类的东西？

Now that is too much complexity, for something that simple. Do you know any better solution?? Something like eRat.B+1 or Enum.Next(Erat.B)?

谢谢

推荐答案

感谢大家的回答和反馈。我惊讶地发现了这么多。查看它们并使用一些想法，我想到了最适合我的解决方案：

Thanks to everybody for your answers and feedback. I was surprised to get so many of them. Looking at them and using some of the ideas, I came up with this solution, which works best for me:

public static class Extensions
{

    public static T Next<T>(this T src) where T : struct
    {
        if (!typeof(T).IsEnum) throw new ArgumentException(String.Format("Argument {0} is not an Enum", typeof(T).FullName));

        T[] Arr = (T[])Enum.GetValues(src.GetType());
        int j = Array.IndexOf<T>(Arr, src) + 1;
        return (Arr.Length==j) ? Arr[0] : Arr[j];
    }
}

这种方法的优点在于，它既简单又通用使用。作为通用扩展方法实现，您可以通过以下方式在任何枚举上调用它：

The beauty of this approach, that it is simple and universal to use. Implemented as generic extension method, you can call it on any enum this way:

return eRat.B.Next();

注意，我使用的是广义扩展方法，因此不需要在调用时指定类型，只是 .Next（）。

Notice, I am using generalized extension method, thus I don't need to specify type upon call, just .Next().

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