C# 检查枚举是否具有等于字符串的字段
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Check if an enum has a field that equals a string
提问by Boris Callens
I have an enum
我有一个枚举
public enum FileExtentions {
mp3,
mpeg
}
And I have a FileInfo of which I want to check if the extension is in the previous enum. I was hoping I could do a
我有一个 FileInfo，我想检查它的扩展名是否在上一个枚举中。我希望我能做一个
FileExtensions.Any(e=>e.ToString().Equals(file.Extension));
But that would have been too awesome. Any ideas?
但这太棒了。有任何想法吗？
采纳答案by Konrad Rudolph
What's the reason behind Any… Equals? Did you overlook Contains?
背后的原因是什么Any…… Equals？你忽略了Contains吗？
bool result = Enum.GetNames(typeof(FileExtensions)).Contains("mp3");
回答by Boris Callens
While pressing submit I thought of the answer myself:
在按下提交时，我自己想到了答案：
Enum.GetNames(typeof(FileExtensions)).Any(f=>f.Equals("."+file.Extension))
回答by Jeff Donnici
You can do that with the System.Enum type:
你可以用 System.Enum 类型做到这一点：
string extension = Enum.GetName(typeof(FileExtensions), FileExtensions.mp3);
if (extension == file.Extension)
// do something here
Update:
更新：
Ah, I misunderstood that you want to check the entire enum for the extension and not that a specific enum value matches the extension. In that case, your approach with GetNames()is the route - sorry you can't mark your own answer as accepted for your own question. ;-)
啊，我误解了您要检查扩展名的整个枚举，而不是特定的枚举值与扩展名匹配。在这种情况下，您使用GetNames() 的方法是路线 - 抱歉，您无法将自己的答案标记为已接受您自己的问题。;-)
回答by huseyint
You can extend the FileInfo type with the following extension method:
您可以使用以下扩展方法扩展 FileInfo 类型：
public static bool HasExtension(this FileInfo file)
{
var ext = file.Extension.StartsWith(".") ? file.Extension.Substring(1)
: file.Extension;
return Enum.GetNames(typeof(FileExtensions))
.Any(f => f.Equals(ext));
}
and use it like:
并使用它：
bool hasExtension = file.HasExtension();
回答by Mark Brackett
Enum.IsDefinedwill take a string containing the name of an enum value. The only ugliness is that you have to strip the leading period off of File.Extensionand it's case sensitive:
Enum.IsDefined将采用包含枚举值名称的字符串。唯一的丑陋之处是您必须从File.Extension 中去除前导句点，并且区分大小写：
Enum.IsDefined(typeof(FileExtension), file.Extension.Substring(1).ToLower())
Edit: Extension method goodness to get close to your desired syntax:
编辑：扩展方法优点以接近您想要的语法：
IEnumerable<string> GetNames(this Type t) {
if (!t.IsEnum) throw new ArgumentException();
return Enum.GetNames(t);
}
typeof(FileExtensions).GetNames().Any(e=>e.ToString().Equals(file.Extension));
Personally, though, I'd still rather the IsDefined route:
不过，就我个人而言，我仍然更喜欢 IsDefined 路线：
bool IsDefined(this Type t, string name) {
if (!t.IsEnum) throw new ArgumentException();
return Enum.IsDefined(t, name);
}
typeof(FileExtension).IsDefined(file.Extension);
回答by Срба
The best way is to use Enum.IsDefined function. It pretty easy, in your case:
最好的方法是使用 Enum.IsDefined 函数。这很容易，就你而言：
if (Enum.IsDefined(typeof(FileExtentions), file.Extension))
回答by Ali Karaca
General solution:
一般解决方案：
Enum.IsDefined(Type, Object)
Your solution is:
您的解决方案是：
Enum.IsDefined(typeof(FileExtentions), FileInfo)
