如何在C#中枚举枚举？
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);
}
}
它给出了以下编译时错误：
“Suit”是“type”，但与“variable”类似
它在第二个Suit关键字上失败。
当前回答
我做了一些扩展以方便枚举的使用。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;
}
}
枚举本身必须用FlagsAttribute修饰：
[Flags]
public enum EnumExample
{
ValueA = 1,
ValueB = 2,
ValueC = 4,
ValueD = 8,
Combi = ValueA | ValueB
}
其他回答
我做了一些扩展以方便枚举的使用。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;
}
}
枚举本身必须用FlagsAttribute修饰：
[Flags]
public enum EnumExample
{
ValueA = 1,
ValueB = 2,
ValueC = 4,
ValueD = 8,
Combi = ValueA | ValueB
}
如果您有：
enum Suit
{
Spades,
Hearts,
Clubs,
Diamonds
}
这：
foreach (var e in Enum.GetValues(typeof(Suit)))
{
Console.WriteLine(e.ToString() + " = " + (int)e);
}
将输出：
Spades = 0
Hearts = 1
Clubs = 2
Diamonds = 3
public void PrintAllSuits()
{
foreach(string suit in Enum.GetNames(typeof(Suits)))
{
Console.WriteLine(suit);
}
}
下面是一个为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()
};
此外，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));
