How can you enumerate an enum
in C#?
E.g. the following code does not compile:
public enum Suit
{
Spades,
Hearts,
Clubs,
Diamonds
}
public void EnumerateAllSuitsDemoMethod()
{
foreach (Suit suit in Suit)
{
DoSomething(suit);
}
}
And it gives the following compile-time error:
'Suit' is a 'type' but is used like a 'variable'
It fails on the Suit
keyword, the second one.
foreach (Suit suit in (Suit[]) Enum.GetValues(typeof(Suit)))
{
}
Note: The cast to (Suit[])
is not strictly necessary, but it does make the code 0.5 ns faster.
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.
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.
I would use Enum.GetValues(typeof(Suit))
instead.
public enum Suits
{
Spades,
Hearts,
Clubs,
Diamonds,
NumSuits
}
public void PrintAllSuits()
{
foreach (var suit in Enum.GetValues(typeof(Suits)))
{
System.Console.WriteLine(suit.ToString());
}
}
Enum.GetValues(typeof(Suits)).OfType<Suits>().ToArray()
. In that case I can iterate array of Suits
enum items, not strings.
Suits suit in Enum.GetValues(typeof(Suits))
?
I made some extensions for easy enum usage. Maybe someone can use it...
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:
[Flags]
public enum EnumExample
{
ValueA = 1,
ValueB = 2,
ValueC = 4,
ValueD = 8,
Combi = ValueA | ValueB
}
where T: Enum
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:
public Enum[] GetValues(Enum enumeration)
{
FieldInfo[] fields = enumeration.GetType().GetFields(BindingFlags.Static | BindingFlags.Public);
Enum[] enumerations = new Enum[fields.Length];
for (var i = 0; i < fields.Length; i++)
enumerations[i] = (Enum) fields[i].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.
return type.GetFields().Where(x => x.IsLiteral).Select(x => x.GetValue(null)).Cast<Enum>();
Use Cast<T>
:
var suits = Enum.GetValues(typeof(Suit)).Cast<Suit>();
There you go, IEnumerable<Suit>
.
from
clause and the foreach
header declarator.
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
.
EnumLoop<Suit>.ForEach((suit) => {
DoSomethingWith(suit);
});
EnumLoop
has this completely generic definition:
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]);
}
}
}
EnumLoop
with some type that is not an enum, it will compile fine, but throw an exception at runtime.
You won't get Enum.GetValues()
in Silverlight.
Original Blog Post by Einar Ingebrigtsen:
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();
}
}
where T: Enum
New .NET 5 Solution:
.NET 5 has introduced a new generic version for the GetValues
method:
Suit[] suitValues = Enum.GetValues<Suit>();
which is now by far the most convenient way of doing this.
Usage in a foreach loop:
foreach (Suit suit in Enum.GetValues<Suit>())
{
}
And for getting enum names:
string[] suitNames = Enum.GetNames<Suit>();
My solution works in .NET Compact Framework (3.5) and supports type checking at compile time:
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.
A call would look like this:
List<MyEnum> result = Utils.GetEnumValues<MyEnum>();
T valueType = default(T)
?
new()
T
. Also, you dont need new T()
at all, you can select just the static fields alone and do .GetValue(null)
. See Aubrey's answer.
where T: Enum
I think you can use
Enum.GetNames(Suit)
public void PrintAllSuits()
{
foreach(string suit in Enum.GetNames(typeof(Suits)))
{
Console.WriteLine(suit);
}
}
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
I think caching the array would speed it up considerably. It looks like you're getting a new array (through reflection) every time. Rather:
Array enums = Enum.GetValues(typeof(Suit));
foreach (Suit suitEnum in enums)
{
DoSomething(suitEnum);
}
That's at least a little faster, ja?
Just by combining the top answers, I threw together a very simple extension:
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 T value) where T : Enum
{
return (T[])Enum.GetValues(typeof (T));
}
}
It is clean, simple, and, by @Jeppe-Stig-Nielsen's comment, fast.
where T: Enum
Three ways:
Enum.GetValues(type) // Since .NET 1.1, not in Silverlight or .NET Compact Framework type.GetEnumValues() // Only on .NET 4 and above type.GetFields().Where(x => x.IsLiteral).Select(x => x.GetValue(null)) // Works everywhere
I am not sure why GetEnumValues
was introduced on type instances. It isn't very readable at all for me.
Having a helper class like Enum<T>
is what is most readable and memorable for me:
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:
Enum<Suit>.GetValues();
// Or
Enum.GetValues(typeof(Suit)); // Pretty consistent style
One can also use some sort of caching if performance matters, but I don't expect this to be an issue at all.
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)));
}
}
There are two ways to iterate an Enum
:
1. var values = Enum.GetValues(typeof(myenum))
2. var values = Enum.GetNames(typeof(myenum))
The first will give you values in form on an array of **object
**s, and the second will give you values in form of an array of **String
**s.
Use it in a foreach
loop as below:
foreach(var value in values)
{
// Do operations here
}
I use ToString() then split and parse the spit array in flags.
[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);
}
I do not hold the opinion this is better, or even good. I am just stating yet another solution.
If enum values range strictly from 0 to n - 1, a generic alternative is:
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:
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...
If you need speed and type checking at build and run time, this helper method is better than using LINQ to cast each element:
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:
static readonly YourEnum[] _values = GetEnumValues<YourEnum>();
Of course you can return IEnumerable<T>
, but that buys you nothing here.
where T: Enum
Here is a working example of creating select options for a DDL:
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()
};
Add method public static IEnumerable<T> GetValues<T>()
to your class, like:
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
:
public static void EnumerateAllSuitsDemoMethod()
{
// Custom method
var foos = GetValues<Suit>();
foreach (var foo in foos)
{
// Do something
}
}
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).)
I know it is a bit messy, but if you are fan of one-liners, here is one:
((Suit[])Enum.GetValues(typeof(Suit))).ToList().ForEach(i => DoSomething(i));
This question appears in Chapter 10 of "C# Step by Step 2013"
The author uses a double for-loop to iterate through a pair of Enumerators (to create a full deck of cards):
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:
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
:
class PlayingCard
{
private readonly Suit suit;
private readonly Value value;
public PlayingCard(Suit s, Value v)
{
this.suit = s;
this.value = v;
}
}
A simple and generic way to convert an enum to something you can interact:
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>();
Dictionary
is not a good idea: if you have an Enum
like enum E { A = 0, B = 0 }
, the 0 value is added 2 times generating an ArgumentException
(you cannot add the same Key
on a Dictionary
2 or more times!).
Dictionary<,>
from a method named ToList
? Also why not return Dictionary<T, string>
?
What if you know the type will be an enum
, but you don't know what the exact type is at compile time?
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.
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));
}
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.
(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.)
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.
EDIT: Should have suggested the System.Enum.GetValues method instead. Oops.
For getting a list of int from an enum, use the following. It works!
List<int> listEnumValues = new List<int>();
YourEnumType[] myEnumMembers = (YourEnumType[])Enum.GetValues(typeof(YourEnumType));
foreach ( YourEnumType enumMember in myEnumMembers)
{
listEnumValues.Add(enumMember.GetHashCode());
}
When you have a bit enum like this
enum DemoFlags
{
DemoFlag = 1,
OtherFlag = 2,
TestFlag = 4,
LastFlag = 8,
}
With this assignement
DemoFlags demoFlags = DemoFlags.DemoFlag | DemoFlags.TestFlag;
and need a result like this
"DemoFlag | TestFlag"
this method helps:
public static string ConvertToEnumString<T>(T enumToConvert, string separator = " | ") where T : Enum
{
StringBuilder convertedEnums = new StringBuilder();
foreach (T enumValue in Enum.GetValues(typeof(T)))
{
if (enumToConvert.HasFlag(enumValue)) convertedEnums.Append($"{ enumValue }{separator}");
}
if (convertedEnums.Length > 0) convertedEnums.Length -= separator.Length;
return convertedEnums.ToString();
}
[Flags]
attribute and using .ToString()
on the value. The separators will be commas instead of pipes. That is: [Flags] enum DemoFlags { ... } //...; return demoFlags.ToString(); But that doesn't answer the question about enumerating the values.
A simple Enum.GetNames(EnumType) should work
Also you can bind to the public static members of the enum directly by using reflection:
typeof(Suit).GetMembers(BindingFlags.Public | BindingFlags.Static)
.ToList().ForEach(x => DoSomething(x.Name));
Success story sharing
enum.GetValues
. You have to use reflection in this case.enum E {A = 0, B = 0}
.Enum.GetValues
results in two values being returned, though they are the same.E.A == E.B
is true, so there is not distinction. If you want individual names, then you should look forEnum.GetNames
.Distinct
extension (since .NET 3.5), soforeach (var suit in ((Suit[])Enum.GetValues(typeof(Suit))).Distinct()) { }
.var
for the type. The compiler will make the variable anObject
instead of the enum. List the enum type explicitly.