如何在 C# 中传递多个枚举值？
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How do you pass multiple enum values in C#?
提问by Ronnie Overby
Sometimes when reading others' C# code I see a method that will accept multiple enum values in a single parameter. I always thought it was kind of neat, but never looked into it.
有时在阅读其他人的 C# 代码时，我看到一个方法会在单个参数中接受多个枚举值。我一直认为它很整洁，但从未仔细研究过。
Well, now I think I may have a need for it, but don't know how to
嗯，现在我想我可能需要它，但不知道如何
- set up the method signature to accept this
- work with the values in the method
- define the enum
- 设置方法签名以接受此
- 使用方法中的值
- 定义枚举
to achieve this sort of thing.
实现这种事情。
在我的特定情况下，我想使用 System.DayOfWeek，其定义为：
[Serializable]
[ComVisible(true)]
public enum DayOfWeek
{
Sunday = 0,
Monday = 1,
Tuesday = 2,
Wednesday = 3,
Thursday = 4,
Friday = 5,
Saturday = 6
}
I want to be able to pass one or more of the DayOfWeek values to my method. Will I be able to use this particular enum as it is? How do I do the 3 things listed above?
我希望能够将一个或多个 DayOfWeek 值传递给我的方法。我能按原样使用这个特定的枚举吗？我如何做上面列出的 3 件事？
采纳答案by Reed Copsey
When you define the enum, just attribute it with [Flags], set values to powers of two, and it will work this way.
当您定义枚举时，只需使用 [Flags] 为其赋予属性，将值设置为 2 的幂，它将以这种方式工作。
Nothing else changes, other than passing multiple values into a function.
除了将多个值传递给函数之外，没有其他任何变化。
For example:
例如：
[Flags]
enum DaysOfWeek
{
Sunday = 1,
Monday = 2,
Tuesday = 4,
Wednesday = 8,
Thursday = 16,
Friday = 32,
Saturday = 64
}
public void RunOnDays(DaysOfWeek days)
{
bool isTuesdaySet = (days & DaysOfWeek.Tuesday) == DaysOfWeek.Tuesday;
if (isTuesdaySet)
//...
// Do your work here..
}
public void CallMethodWithTuesdayAndThursday()
{
this.RunOnDays(DaysOfWeek.Tuesday | DaysOfWeek.Thursday);
}
For more details, see MSDN's documentation on Enumeration Types.
有关更多详细信息，请参阅MSDN 关于枚举类型的文档。
Edit in response to additions to question.
编辑以回应问题的补充。
You won't be able to use that enum as is, unless you wanted to do something like pass it as an array/collection/params array. That would let you pass multiple values. The flags syntax requires the Enum to be specified as flags (or to bastardize the language in a way that's its not designed).
您将无法按原样使用该枚举，除非您想执行诸如将其作为数组/集合/参数数组传递之类的操作。那会让你传递多个值。标志语法要求将 Enum 指定为标志（或以非设计的方式对语言进行混蛋）。
回答by Andrew Siemer
Something of this nature should show what you are looking for:
这种性质的东西应该显示你正在寻找什么：
[Flags]
public enum SomeName
{
Name1,
Name2
}
public class SomeClass()
{
public void SomeMethod(SomeName enumInput)
{
...
}
}
回答by Jacob
I second Reed's answer. However, when creating the enum, you must specify the values for each enum member so it makes a sort of bit field. For example:
我支持 Reed 的回答。但是，在创建枚举时，您必须为每个枚举成员指定值，以便它成为一种位字段。例如：
[Flags]
public enum DaysOfWeek
{
Sunday = 1,
Monday = 2,
Tuesday = 4,
Wednesday = 8,
Thursday = 16,
Friday = 32,
Saturday = 64,
None = 0,
All = Weekdays | Weekend,
Weekdays = Monday | Tuesday | Wednesday | Thursday | Friday,
Weekend = Sunday | Saturday,
// etc.
}
回答by Rony
[Flags]
public enum DaysOfWeek{
Sunday = 1 << 0,
Monday = 1 << 1,
Tuesday = 1 << 2,
Wednesday = 1 << 3,
Thursday = 1 << 4,
Friday = 1 << 5,
Saturday = 1 << 6
}
call the method in this format
以这种格式调用方法
MethodName(DaysOfWeek.Tuesday | DaysOfWeek.Thursday);
MethodName(DaysOfWeek.Tuesday | DaysOfWeek.Thursday);
Implement a EnumToArray method to get the options passed
实现 EnumToArray 方法以获取传递的选项
private static void AddEntryToList(DaysOfWeek days, DaysOfWeek match, List<string> dayList, string entryText) {
if ((days& match) != 0) {
dayList.Add(entryText);
}
}
internal static string[] EnumToArray(DaysOfWeek days) {
List<string> verbList = new List<string>();
AddEntryToList(days, HttpVerbs.Sunday, dayList, "Sunday");
AddEntryToList(days, HttpVerbs.Monday , dayList, "Monday ");
...
return dayList.ToArray();
}
回答by Tetraneutron
[Flags]
public enum DaysOfWeek
{
Mon = 1,
Tue = 2,
Wed = 4,
Thur = 8,
Fri = 16,
Sat = 32,
Sun = 64
}
You have to specify the numbers, and increment them like this because it is storing the values in a bitwise fashion.
您必须指定数字，并像这样递增它们，因为它以按位方式存储值。
Then just define your method to take this enum
然后只需定义您的方法来获取此枚举
public void DoSomething(DaysOfWeek day)
{
...
}
and to call it do something like
并称之为做类似的事情
DoSomething(DaysOfWeek.Mon | DaysOfWeek.Tue) // Both Monday and Tuesday
To check if one of the enum values was included check them using bitwise operations like
要检查是否包含枚举值之一，请使用按位运算检查它们，例如
public void DoSomething(DaysOfWeek day)
{
if ((day & DaysOfWeek.Mon) == DaysOfWeek.Mon) // Does a bitwise and then compares it to Mondays enum value
{
// Monday was passed in
}
}
回答by statenjason
Mark your enum with the [Flags] attribute. Also ensure that all of your values are mutually exclusive (two values can't add up to equal another) like 1,2,4,8,16,32,64 in your case
使用 [Flags] 属性标记您的枚举。还要确保您的所有值都是互斥的（两个值不能加起来等于另一个值），例如在您的情况下为 1,2,4,8,16,32,64
[Flags]
public enum DayOfWeek
{
Sunday = 1,
Monday = 2,
Tuesday = 4,
Wednesday = 8,
Thursday = 16,
Friday = 32,
Saturday = 64
}
When you have a method that accepts a DayOfWeek enum use the bitwise or operator (|) to use multiple members together. For example:
当您有一个接受 DayOfWeek 枚举的方法时，请使用按位或运算符 (|) 将多个成员一起使用。例如：
MyMethod(DayOfWeek.Sunday|DayOfWeek.Tuesday|DayOfWeek.Friday)
To check if the parameter contains a specific member, use the bitwise andoperator (&) with the member you are checking for.
要检查参数是否包含特定成员，请对要检查的成员使用按位和运算符 (&)。
if(arg & DayOfWeek.Sunday == DayOfWeek.Sunday)
Console.WriteLine("Contains Sunday");
回答by Dan
Reed Copsey is correct and I would add to the original post if I could, but I cant so I'll have to reply instead.
Reed Copsey 是正确的，如果可以，我会添加到原始帖子中，但我不能，所以我必须回复。
Its dangerous to just use [Flags] on any old enum. I believe you have to explicitly change the enum values to powers of two when using flags, to avoid clashes in the values. See the guidelines for FlagsAttribute and Enum.
在任何旧的枚举上只使用 [Flags] 是危险的。我相信您必须在使用标志时将枚举值显式更改为 2 的幂，以避免值发生冲突。请参阅FlagsAttribute 和 Enum的指南。
回答by Ronnie Overby
With the help of the posted answers and these:
在发布的答案和这些的帮助下：
- FlagsAttribute Class(Look at the comparison of using and not using the [Flags] attribute)
- Enum Flags Attribute
- FlagsAttribute 类（看使用和不使用[Flags]属性的对比）
- 枚举标志属性
I feel like I understand it pretty well.
我觉得我理解得很好。
Thanks.
谢谢。
回答by Robert Paulson
In my particular situation, I would like to use the System.DayOfWeek
在我的特殊情况下，我想使用 System.DayOfWeek
You can not use the System.DayOfWeek as a [Flags]enumeration because you have no control over it. If you wish to have a method that accepts multiple DayOfWeekthen you will have to use the paramskeyword
您不能使用 System.DayOfWeek 作为[Flags]枚举，因为您无法控制它。如果您希望有一个接受多个的方法，DayOfWeek那么您将不得不使用params关键字
void SetDays(params DayOfWeek[] daysToSet)
{
if (daysToSet == null || !daysToSet.Any())
throw new ArgumentNullException("daysToSet");
foreach (DayOfWeek day in daysToSet)
{
// if( day == DayOfWeek.Monday ) etc ....
}
}
SetDays( DayOfWeek.Monday, DayOfWeek.Sunday );
Otherwise you can create your own [Flags]enumeration as outlined by numerous other responders and use bitwise comparisons.
否则，您可以创建自己的[Flags]枚举，如许多其他响应者所述，并使用按位比较。
回答by Tillito
I think the more elegant solution is to use HasFlag():
我认为更优雅的解决方案是使用 HasFlag()：
[Flags]
public enum DaysOfWeek
{
Sunday = 1,
Monday = 2,
Tuesday = 4,
Wednesday = 8,
Thursday = 16,
Friday = 32,
Saturday = 64
}
public void RunOnDays(DaysOfWeek days)
{
bool isTuesdaySet = days.HasFlag(DaysOfWeek.Tuesday);
if (isTuesdaySet)
{
//...
}
}
public void CallMethodWithTuesdayAndThursday()
{
RunOnDays(DaysOfWeek.Tuesday | DaysOfWeek.Thursday);
}
