如何在C＃中枚举枚举？

How can you enumerate an enum in C#?

你怎么能枚举C#中的枚举?

E.g. the following code does not compile:

例如。以下代码无法编译:

public enum Suit 
{
    Spades,
    Hearts,
    Clubs,
    Diamonds
}

public void EnumerateAllSuitsDemoMethod() 
{
    foreach (Suit suit in Suit) 
    {
        DoSomething(suit);
    }
}

And gives the following compile-time error:

并给出以下编译时错误:

'Suit' is a 'type' but is used like a 'variable'

'Suit'是'type',但用作'变量'

It fails on the Suit keyword, the second one.

它在Suit关键字上失败,第二个。

26 个解决方案

#1

foreach (Suit suit in (Suit[]) Enum.GetValues(typeof(Suit)))
{
}

#2

It looks to me like you really want to print out the names of each enum, rather than the values. In which case Enum.GetNames() seems to be the right approach.

在我看来,你真的想要打印每个枚举的名称,而不是值。在这种情况下,Enum.GetNames()似乎是正确的方法。

public enum Suits
{
    Spades,
    Hearts,
    Clubs,
    Diamonds,
    NumSuits
}

public void PrintAllSuits()
{
    foreach (string name in Enum.GetNames(typeof(Suits)))
    {
        System.Console.WriteLine(name);
    }
}

By the way, incrementing the value is not a good way to enumerate the values of an enum. You should do this instead.

顺便说一下,递增值不是枚举枚举值的好方法。你应该这样做。

I would use Enum.GetValues(typeof(Suit)) instead.

我会使用Enum.GetValues(typeof(Suit))代替。

public enum Suits
{
    Spades,
    Hearts,
    Clubs,
    Diamonds,
    NumSuits
}

public void PrintAllSuits()
{
    foreach (var suit in Enum.GetValues(typeof(Suits)))
    {
        System.Console.WriteLine(suit.ToString());
    }
}

#3

I made some extensions for easy enum usage, maybe someone can use it...

我做了一些扩展以便轻松使用枚举,也许有人可以使用它...

public static class EnumExtensions
{
    /// <summary>
    /// Gets all items for an enum value.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">The value.</param>
    /// <returns></returns>
    public static IEnumerable<T> GetAllItems<T>(this Enum value)
    {
        foreach (object item in Enum.GetValues(typeof(T)))
        {
            yield return (T)item;
        }
    }

    /// <summary>
    /// Gets all items for an enum type.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">The value.</param>
    /// <returns></returns>
    public static IEnumerable<T> GetAllItems<T>() where T : struct
    {
        foreach (object item in Enum.GetValues(typeof(T)))
        {
            yield return (T)item;
        }
    }

    /// <summary>
    /// Gets all combined items from an enum value.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">The value.</param>
    /// <returns></returns>
    /// <example>
    /// Displays ValueA and ValueB.
    /// <code>
    /// EnumExample dummy = EnumExample.Combi;
    /// foreach (var item in dummy.GetAllSelectedItems<EnumExample>())
    /// {
    ///    Console.WriteLine(item);
    /// }
    /// </code>
    /// </example>
    public static IEnumerable<T> GetAllSelectedItems<T>(this Enum value)
    {
        int valueAsInt = Convert.ToInt32(value, CultureInfo.InvariantCulture);

        foreach (object item in Enum.GetValues(typeof(T)))
        {
            int itemAsInt = Convert.ToInt32(item, CultureInfo.InvariantCulture);

            if (itemAsInt == (valueAsInt & itemAsInt))
            {
                yield return (T)item;
            }
        }
    }

    /// <summary>
    /// Determines whether the enum value contains a specific value.
    /// </summary>
    /// <param name="value">The value.</param>
    /// <param name="request">The request.</param>
    /// <returns>
    ///     <c>true</c> if value contains the specified value; otherwise, <c>false</c>.
    /// </returns>
    /// <example>
    /// <code>
    /// EnumExample dummy = EnumExample.Combi;
    /// if (dummy.Contains<EnumExample>(EnumExample.ValueA))
    /// {
    ///     Console.WriteLine("dummy contains EnumExample.ValueA");
    /// }
    /// </code>
    /// </example>
    public static bool Contains<T>(this Enum value, T request)
    {
        int valueAsInt = Convert.ToInt32(value, CultureInfo.InvariantCulture);
        int requestAsInt = Convert.ToInt32(request, CultureInfo.InvariantCulture);

        if (requestAsInt == (valueAsInt & requestAsInt))
        {
            return true;
        }

        return false;
    }
}

The enum itself must be decorated with the FlagsAttribute

枚举本身必须使用FlagsAttribute进行修饰

[Flags]
public enum EnumExample
{
    ValueA = 1,
    ValueB = 2,
    ValueC = 4,
    ValueD = 8,
    Combi = ValueA | ValueB
}

#4

Some versions of the .NET framework do not support Enum.GetValues. Here's a good workaround from Ideas 2.0: Enum.GetValues in Compact Framework:

某些版本的.NET框架不支持Enum.GetValues。以下是Ideas 2.0中的一个很好的解决方法:Compact Framework中的Enum.GetValues:

public List<Enum> GetValues(Enum enumeration)
{
   List<Enum> enumerations = new List<Enum>();
   foreach (FieldInfo fieldInfo in enumeration.GetType().GetFields(
         BindingFlags.Static | BindingFlags.Public))
   {
      enumerations.Add((Enum)fieldInfo.GetValue(enumeration));
   }
   return enumerations;
}

As with any code that involves reflection, you should take steps to ensure it runs only once and results are cached.

与涉及反射的任何代码一样,您应该采取措施确保它只运行一次并缓存结果。

#5

I think this is more efficient than other suggestions because GetValues() is not called each time you have a loop. It is also more concise. And you get a compile-time error not a runtime exception if Suit is not an enum.

我认为这比其他建议更有效,因为每次循环时都不会调用GetValues()。它也更简洁。如果Suit不是枚举,则会出现编译时错误,而不是运行时异常。

EnumLoop<Suit>.ForEach((suit) => {
    DoSomethingWith(suit);
});

EnumLoop has this completely generic definition:

EnumLoop有这个完全通用的定义:

class EnumLoop<Key> where Key : struct, IConvertible {
    static readonly Key[] arr = (Key[])Enum.GetValues(typeof(Key));
    static internal void ForEach(Action<Key> act) {
        for (int i = 0; i < arr.Length; i++) {
            act(arr[i]);
        }
    }
}

#6

Why is no one using Cast<T>?

为什么没有人使用Cast ?

var suits = Enum.GetValues(typeof(Suit)).Cast<Suit>();

There you go IEnumerable<Suit>.

你去IEnumerable 。

#7

You won't get Enum.GetValues() in Silverlight.

你不会在Silverlight中获得Enum.GetValues()。

Original Blog Post by Einar Ingebrigtsen:

Einar Ingebrigtsen的原始博文:

public class EnumHelper
{
    public static T[] GetValues<T>()
    {
        Type enumType = typeof(T);

        if (!enumType.IsEnum)
        {
            throw new ArgumentException("Type '" + enumType.Name + "' is not an enum");
        }

        List<T> values = new List<T>();

        var fields = from field in enumType.GetFields()
                     where field.IsLiteral
                     select field;

        foreach (FieldInfo field in fields)
        {
            object value = field.GetValue(enumType);
            values.Add((T)value);
        }

        return values.ToArray();
    }

    public static object[] GetValues(Type enumType)
    {
        if (!enumType.IsEnum)
        {
            throw new ArgumentException("Type '" + enumType.Name + "' is not an enum");
        }

        List<object> values = new List<object>();

        var fields = from field in enumType.GetFields()
                     where field.IsLiteral
                     select field;

        foreach (FieldInfo field in fields)
        {
            object value = field.GetValue(enumType);
            values.Add(value);
        }

        return values.ToArray();
    }
}

#8

Just to add my solution, which works in compact framework (3.5) and supports type checking at compile time:

只是添加我的解决方案,它在紧凑的框架(3.5)中工作,并支持在编译时进行类型检查:

public static List<T> GetEnumValues<T>() where T : new() {
    T valueType = new T();
    return typeof(T).GetFields()
        .Select(fieldInfo => (T)fieldInfo.GetValue(valueType))
        .Distinct()
        .ToList();
}

public static List<String> GetEnumNames<T>() {
    return typeof (T).GetFields()
        .Select(info => info.Name)
        .Distinct()
        .ToList();
}

- If anyone knows how to get rid of the T valueType = new T(), I'd be happy to see a solution.

- 如果有人知道如何摆脱T valueType = new T(),我很乐意看到解决方案。

A call would look like this:

一个电话看起来像这样:

List<MyEnum> result = Utils.GetEnumValues<MyEnum>();

#9

I think you can use

我想你可以用

Enum.GetNames(Suit)

#10

public void PrintAllSuits()
{
    foreach(string suit in Enum.GetNames(typeof(Suits)))
    {
        Console.WriteLine(suit);
    }
}

#11

foreach (Suit suit in Enum.GetValues(typeof(Suit))) { }

I've heard vague rumours that this is terifically slow. Anyone know? – Orion Edwards Oct 15 '08 at 1:31 7

我听到一些含糊不清的谣言说这种情况非常缓慢。谁知道? - 猎户座爱德华兹08年10月15日1:31 7

I think caching the array would speed it up considerably. It looks like you're getting a new array (through reflection) every time. Rather:

我认为缓存阵列会大大加快它的速度。看起来你每次都会得到一个新阵列(通过反射)。而是:

Array enums = Enum.GetValues(typeof(Suit));
foreach (Suit suitEnum in enums) 
{
    DoSomething(suitEnum);
}

That's at least a little faster, ja?

这至少要快一点,ja?

#12

Three ways:

1. Enum.GetValues(type) //since .NET 1.1, not in silverlight or compact framewok
2. type.GetEnumValues() //only on .NET 4 and above
3. type.GetFields().Where(x => x.IsLiteral).Select(x => x.GetValue(null)) //works everywhere

Not sure why was GetEnumValues introduced on type instance, it isn't very readable at all for me.

不确定为什么GetEnumValues在类型实例上引入,它对我来说根本不是很可读。

---

Having a helper class like Enum<T> is what is most readable and memorable for me:

像Enum 这样的助手类对我来说是最具可读性和难忘性的:

public static class Enum<T> where T : struct, IComparable, IFormattable, IConvertible
{
    public static IEnumerable<T> GetValues()
    {
        return (T[])Enum.GetValues(typeof(T));
    }

    public static IEnumerable<string> GetNames()
    {
        return Enum.GetNames(typeof(T));
    }
}

Now you call:

现在你打电话:

Enum<Suit>.GetValues();
//or
Enum.GetValues(typeof(Suit)); //pretty consistent style

One can also use sort of caching if performance matters, but I don't expect this to be an issue at all

如果性能很重要,也可以使用某种缓存,但我不认为这根本就是一个问题

public static class Enum<T> where T : struct, IComparable, IFormattable, IConvertible
{
    //lazily loaded
    static T[] values;
    static string[] names;

    public static IEnumerable<T> GetValues()
    {
        return values ?? (values = (T[])Enum.GetValues(typeof(T)));
    }

    public static IEnumerable<string> GetNames()
    {
        return names ?? (names = Enum.GetNames(typeof(T)));
    }
}

#13

What the hell I'll throw my two pence in, just by combining the top answers I through together a very simple extension

我将把我的两便士扔进去,只需将最顶层的答案结合在一起,我就可以通过一个非常简单的扩展

public static class EnumExtensions
{
    /// <summary>
    /// Gets all items for an enum value.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="value">The value.</param>
    /// <returns></returns>
    public static IEnumerable<T> GetAllItems<T>(this Enum value)
    {
        return (T[])Enum.GetValues(typeof (T));
    }
}

Clean simple and by @Jeppe-Stig-Nielsen s comment fast.

干净简单,并由@ Jeppe-Stig-Nielsen快速评论。

#14

I use ToString() then split and parse the spit array in flags.

我使用ToString()然后拆分并解析标志中的spit数组。

[Flags]
public enum ABC {
   a = 1,
   b = 2,
   c = 4
};

public IEnumerable<ABC> Getselected (ABC flags)
{
   var values = flags.ToString().Split(',');
   var enums = values.Select(x => (ABC)Enum.Parse(typeof(ABC), x.Trim()));
   return enums;
}

ABC temp= ABC.a | ABC.b;
var list = getSelected (temp);
foreach (var item in list)
{
   Console.WriteLine(item.ToString() + " ID=" + (int)item);
}

#15

There are two ways to iterate an Enum:

迭代枚举有两种方法:

1. var values =  Enum.GetValues(typeof(myenum))
2. var values =  Enum.GetNames(typeof(myenum))

The first will give you values in form on a array of object, and the second will give you values in form of array of String.

第一个将在对象数组中为您提供表单中的值,第二个将以String数组的形式为您提供值。

Use it in foreach loop as below:

在foreach循环中使用它如下:

foreach(var value in values)
{
    //Do operations here
}

#16

I do not hold the opinion this is better, or even good, just stating yet another solution.

If enum values range strictly from 0 to n - 1, a generic alternative:

如果枚举值严格范围从0到n - 1,则通用替代方法:

public void EnumerateEnum<T>()
{
    int length = Enum.GetValues(typeof(T)).Length;
    for (var i = 0; i < length; i++)
    {
        var @enum = (T)(object)i;
    }
}

If enum values are contiguous and you can provide the first and last element of the enum, then:

如果枚举值是连续的,并且您可以提供枚举的第一个和最后一个元素,那么:

public void EnumerateEnum()
{
    for (var i = Suit.Spade; i <= Suit.Diamond; i++)
    {
        var @enum = i;
    }
}

but that's not strictly enumerating, just looping. The second method is much faster than any other approach though...

但这不是严格的枚举,只是循环。第二种方法比任何其他方法快得多......

#17

If you need speed and type checking at build and run time, this helper method is better than using LINQ to cast each element:

如果在构建和运行时需要速度和类型检查,这个辅助方法比使用LINQ强制转换每个元素更好:

public static T[] GetEnumValues<T>() where T : struct, IComparable, IFormattable, IConvertible
{
    if (typeof(T).BaseType != typeof(Enum))
    {
        throw new ArgumentException(string.Format("{0} is not of type System.Enum", typeof(T)));
    }
    return Enum.GetValues(typeof(T)) as T[];
}

And you can use it like below:

你可以像下面这样使用它:

static readonly YourEnum[] _values = GetEnumValues<YourEnum>();

Of course you can return IEnumerable<T>, but that buys you nothing here.

当然你可以返回IEnumerable ,但是这里没有你买的东西。

#18

here is a working example of creating select options for a DDL

这是为DDL创建选择选项的工作示例

var resman = ViewModelResources.TimeFrame.ResourceManager;

ViewBag.TimeFrames = from MapOverlayTimeFrames timeFrame 
      in Enum.GetValues(typeof(MapOverlayTimeFrames))
      select new SelectListItem
      {
         Value = timeFrame.ToString(),
         Text = resman.GetString(timeFrame.ToString()) ?? timeFrame.ToString()
      };

#19

foreach (Suit suit in Enum.GetValues(typeof(Suit)))
{
}

(The current accepted answer has a cast that I don't think is needed (although I may be wrong).)

(目前接受的答案有一个我认为不需要的演员(尽管我可能错了)。)

#20

This question appears in Chapter 10 of "C# Step by Step 2013"

这个问题出现在“C#Step by Step 2013”​​的第10章中

The author uses a double for-loop to iterate through a pair of Enumerators (to create a full deck of cards):

作者使用双循环来迭代一对枚举器(以创建一副完整的卡片):

class Pack
{
    public const int NumSuits = 4;
    public const int CardsPerSuit = 13;
    private PlayingCard[,] cardPack;

    public Pack()
    {
        this.cardPack = new PlayingCard[NumSuits, CardsPerSuit];
        for (Suit suit = Suit.Clubs; suit <= Suit.Spades; suit++)
        {
            for (Value value = Value.Two; value <= Value.Ace; value++)
            {
                cardPack[(int)suit, (int)value] = new PlayingCard(suit, value);
            }
        }
    }
}

In this case, Suit and Value are both enumerations:

在这种情况下,Suit和Value都是枚举:

enum Suit { Clubs, Diamonds, Hearts, Spades }
enum Value { Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King, Ace}

and PlayingCard is a card object with a defined Suit and Value:

和PlayingCard是一个具有定义的套装和价值的卡片对象:

class PlayingCard
{
    private readonly Suit suit;
    private readonly Value value;

    public PlayingCard(Suit s, Value v)
    {
        this.suit = s;
        this.value = v;
    }
}

#21

I know it is a bit messy but if you are fan of one-liners, here is one:

我知道它有点乱,但如果你是单行的粉丝,这里有一个:

((Suit[])Enum.GetValues(typeof(Suit))).ToList().ForEach(i => DoSomething(i));

#22

A simple and generic way to convert an enum to something you can interact:

将枚举转换为可以交互的内容的简单通用方法:

public static Dictionary<int, string> ToList<T>() where T : struct
{
   return ((IEnumerable<T>)Enum
       .GetValues(typeof(T)))
       .ToDictionary(
           item => Convert.ToInt32(item),
           item => item.ToString());
}

And then:

var enums = EnumHelper.ToList<MyEnum>();

#23

What if you know the type will be an enum, but you don't know what the exact type is at compile time?

如果您知道类型将是枚举,但您不知道编译时的确切类型是什么?

public class EnumHelper
{
    public static IEnumerable<T> GetValues<T>()
    {
        return Enum.GetValues(typeof(T)).Cast<T>();
    }

    public static IEnumerable getListOfEnum(Type type)
    {
        MethodInfo getValuesMethod = typeof(EnumHelper).GetMethod("GetValues").MakeGenericMethod(type);
        return (IEnumerable)getValuesMethod.Invoke(null, null);
    }
}

The method getListOfEnum uses reflection to take any enum type and returns an IEnumerable of all enum values.

方法getListOfEnum使用反射来获取任何枚举类型并返回所有枚举值的IEnumerable。

Usage:

Type myType = someEnumValue.GetType();

IEnumerable resultEnumerable = getListOfEnum(myType);

foreach (var item in resultEnumerable)
{
    Console.WriteLine(String.Format("Item: {0} Value: {1}",item.ToString(),(int)item));
}

#24

Add method public static IEnumerable<T> GetValues<T>() to your class, like

添加方法public static IEnumerable GetValues ()到你的类,比如

public static IEnumerable<T> GetValues<T>()
{
    return Enum.GetValues(typeof(T)).Cast<T>();
}

call and pass your enum, now you can iterate through it using foreach

调用并传递你的枚举,现在你可以使用foreach迭代它

 public static void EnumerateAllSuitsDemoMethod()
 {
     // custom method
     var foos = GetValues<Suit>(); 
     foreach (var foo in foos)
     {
         // Do something
     }
 }

#25

Also you can bind to the public static members of the enum directly by using reflection:

您还可以使用反射直接绑定到枚举的公共静态成员:

typeof(Suit).GetMembers(BindingFlags.Public | BindingFlags.Static)
    .ToList().ForEach(x => DoSomething(x.Name));

#26

enum types are called "enumeration types" not because they are containers that "enumerate" values (which they aren't), but because they are defined by enumerating the possible values for a variable of that type.

枚举类型被称为“枚举类型”,不是因为它们是“枚举”值(它们不是)的容器,而是因为它们是通过枚举该类型变量的可能值来定义的。

(Actually, that's a bit more complicated than that - enum types are considered to have an "underlying" integer type, which means each enum value corresponds to an integer value (this is typically implicit, but can be manually specified). C# was designed in a way so that you could stuff any integer of that type into the enum variable, even if it isn't a "named" value.)

(实际上,这有点复杂 - 枚举类型被认为具有“底层”整数类型,这意味着每个枚举值对应一个整数值(这通常是隐式的,但可以手动指定).C#是设计的在某种程度上,你可以将任何类型的整数填充到枚举变量中,即使它不是“命名”值。)

The System.Enum.GetNames method can be used to retrieve an array of strings which are the names of the enum values, as the name suggests.

System.Enum.GetNames方法可用于检索字符串数组,这些字符串是枚举值的名称,顾名思义。

EDIT: Should have suggested the System.Enum.GetValues method instead. Oops.

编辑:应该建议使用System.Enum.GetValues方法。哎呀。