How do I cast int to enum in C#?

Question

How do I cast an int to an enum in C#?

Uncaused

Answer 1

From an int:

YourEnum foo = (YourEnum)yourInt;

From a string:

YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);

// The foo.ToString().Contains(",") check is necessary for 
// enumerations marked with a [Flags] attribute.
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
    throw new InvalidOperationException(
        $"{yourString} is not an underlying value of the YourEnum enumeration."
    );
}

From a number:

YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum), yourInt);

Rejuvenate

That correct it should be: YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString) OR YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourInt) -- As applicable. – Capri

@FlySwat, what if YourEnum is dynamic and will only be known at runtime, and what I want is to convert to Enum? – Southeast

@Shimmy. If the enum is only known at runtime, keep it dynamic. Type safety (strong typing) can only be guaranteed by the compiler anyway. You cannot strongly type an object at runtime. The closest you can come to it is by using generics, but the generic type must be known at compile time. T ToEnum<T>(int x) { return (T)x; } but there is no real advantage over casting directly. – Roveover

Quick question, if you were to go back from YourEnum foo to int anInt type: anInt = (int)foo; would that work? – Yoakum

@Yoakum Sure, it works. (If the underlying integer type of the enum is not int, cast to that underlying integer type instead. But it is extremely rare that the underlying type should be something else than simply int.) – Coinsurance

Be aware that Enum.Parse will NOT work if your code is obfuscated. At run time after obfuscation the string is compared to the enum names, and at this point the names of the enums aren't what you would expect them to be. Your parse will fail where they succeeded before as a result. – Sine

BEWARE If you use the "from a string" syntax above and pass in an invalid string that is a number (e.g. "2342342" -- assuming that's not a value of your enum), it will actually allow that without throwing an error! Your enum will have that value (2342342) even though it's not a valid choice in the enum itself. – Slav

I think this answer is a bit dated now. For string, you should really be using var result = Enum.TryParse(yourString, out yourEnum) nowadays (and checking the result to determine if the conversion failed). – Stipulate

@JustinTConroy I don't know if I agree with that. In my programs, if the conversion fails it's often a non-recoverable error, so I want the exception to be thrown. – Sleeper

The Parse function presents a classic example of a vexing exception. That is, an exception that is thrown in a completely non-exceptional circumstance, usually due to an unfortunate design decision. The developers of C# recognized this unfortunate design and later added TryParse to deal with this. TryParse returns a boolean that indicates if the parse succeeded or failed, so you should use that boolean instead of an exception handler. See Eric Lippert's blog post about vexing exceptions for more information. – Stipulate

It is also possible to have Enum.Parse be case-insensitive by adding a true parameter value to the call: YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString, true); – Officeholder

Is it possible that the conversion from int works even if the int value is not present in the enum? I just tried it in .net 3.5 and it seems to work which is quite confusing. – Lowpressure

Enum.ToObject was what I was looking for. This is exactly what you need when working with enums dynamically and you have a type that you know is an enum but can't prove it to the compiler, which won't allow you to cast from an int value to an arbitrary type. – Anamorphism

@Lowpressure Yes, there is Enum.IsDefined() to check if the value you want to convert exists in your enum. – Sevigny

@JustinTConroy Except that it's not. When you call Parse, you trust the input value to be correct, and when it isn't, it's a bug in the code (and there's an exception as there should be). If you're dealing with user input, you should always call TryParse, because invalid input isn't exceptional. The article you linked mentions this in "the 99% use case for this method is transforming strings input by the user", that's the bug, the method isn't designed to handle user input, TryParse is. – Tare

BEWARE this does act like zero-based array enumeration! csharprepl test code: ``` > public enum Test : int { One, Two, Three, Four } > var x = 3; > (Test)x Four ``` – Nich

Answer 2

Just cast it:

MyEnum e = (MyEnum)3;

Check if it's in range using Enum.IsDefined:

if (Enum.IsDefined(typeof(MyEnum), 3)) { ... }

Jennie

Beware you can't use Enum.IsDefined if you use the Flags attribute and the value is a combination of flags for example: Keys.L | Keys.Control – Holcomb

Regarding Enum.IsDefined, be aware that it can be dangerous: msdn.microsoft.com/en-us/library/ms229025(VS.90).aspx – Lambdacism

I prefer this definition: "Returns an indication whether a constant with a specified value exists in a specified enumeration" from MSDN – Cargill

...Because your definition can be misleading, because you are saying: "...check if it's in range..." which implies within a range of numbers with starting and ending limits... – Cargill

Note that an Enum's value is int by default, but that can be changed which may make the cast dangerous. Check @atlastes's answer. – Roemer

@Lambdacism can you provide a succinct example of a dangerous scenario? Having trouble wrapping my head around that doc. – Hoicks

@mac9416 I've tried to give a succinct example at gist.github.com/alowdon/f7354cda97bac70b44e1c04bc0991bcc - basically by using IsDefined to check input values, you leave yourself vulnerable to people adding new enum values later which would pass an IsDefined check (since the new value exists in the new code), but which might not work with the original code you wrote. It's therefore safer to explicitly specify the enum values that your code is able to handle. – Lambdacism

Answer 3

Alternatively, use an extension method instead of a one-liner:

public static T ToEnum<T>(this string enumString)
{
    return (T) Enum.Parse(typeof (T), enumString);
}

Usage:

Color colorEnum = "Red".ToEnum<Color>();

OR

string color = "Red";
var colorEnum = color.ToEnum<Color>();

Pied

For processing user input, it's probably a good idea to call the overload of Enum.Parse that is allows you to specify that the comparison NOT be case sensitive (i.e. a user typing "red" (lowercase) would crash the above code without this change.) – Capitoline

Handy, but the question specifically asks about ints. – Chagall

this also works if the string is an integer, e.g. "2" – Friday

This will throw an exception if enumString is null (had a similar issue yesterday). Consider using TryParse instead of Parse. TryParse will also check if T is an Enum Type – Prophase

This type of extension method on System.String seems like namespace pollution – Vedanta

Answer 4

I think to get a complete answer, people have to know how enums work internally in .NET.

How stuff works

An enum in .NET is a structure that maps a set of values (fields) to a basic type (the default is int). However, you can actually choose the integral type that your enum maps to:

public enum Foo : short

In this case the enum is mapped to the short data type, which means it will be stored in memory as a short and will behave as a short when you cast and use it.

If you look at it from a IL point of view, a (normal, int) enum looks like this:

.class public auto ansi serializable sealed BarFlag extends System.Enum
{
    .custom instance void System.FlagsAttribute::.ctor()
    .custom instance void ComVisibleAttribute::.ctor(bool) = { bool(true) }

    .field public static literal valuetype BarFlag AllFlags = int32(0x3fff)
    .field public static literal valuetype BarFlag Foo1 = int32(1)
    .field public static literal valuetype BarFlag Foo2 = int32(0x2000)

    // and so on for all flags or enum values

    .field public specialname rtspecialname int32 value__
}

What should get your attention here is that the value__ is stored separately from the enum values. In the case of the enum Foo above, the type of value__ is int16. This basically means that you can store whatever you want in an enum, as long as the types match.

At this point I'd like to point out that System.Enum is a value type, which basically means that BarFlag will take up 4 bytes in memory and Foo will take up 2 -- e.g. the size of the underlying type (it's actually more complicated than that, but hey...).

The answer

So, if you have an integer that you want to map to an enum, the runtime only has to do 2 things: copy the 4 bytes and name it something else (the name of the enum). Copying is implicit because the data is stored as value type - this basically means that if you use unmanaged code, you can simply interchange enums and integers without copying data.

To make it safe, I think it's a best practice to know that the underlying types are the same or implicitly convertible and to ensure the enum values exist (they aren't checked by default!).

To see how this works, try the following code:

public enum MyEnum : int
{
    Foo = 1,
    Bar = 2,
    Mek = 5
}

static void Main(string[] args)
{
    var e1 = (MyEnum)5;
    var e2 = (MyEnum)6;

    Console.WriteLine("{0} {1}", e1, e2);
    Console.ReadLine();
}

Note that casting to e2 also works! From the compiler perspective above this makes sense: the value__ field is simply filled with either 5 or 6 and when Console.WriteLine calls ToString(), the name of e1 is resolved while the name of e2 is not.

If that's not what you intended, use Enum.IsDefined(typeof(MyEnum), 6) to check if the value you are casting maps to a defined enum.

Also note that I'm explicit about the underlying type of the enum, even though the compiler actually checks this. I'm doing this to ensure I don't run into any surprises down the road. To see these surprises in action, you can use the following code (actually I've seen this happen a lot in database code):

public enum MyEnum : short
{
    Mek = 5
}

static void Main(string[] args)
{
    var e1 = (MyEnum)32769; // will not compile, out of bounds for a short

    object o = 5;
    var e2 = (MyEnum)o;     // will throw at runtime, because o is of type int

    Console.WriteLine("{0} {1}", e1, e2);
    Console.ReadLine();
}

Greenhouse

Fantastic answer, thanks! In your last code sample, it throws an exception at runtime because o is an object. You can cast an int variable to a short as long as it falls within the short range. – Audun

@Audun Thanks. Actually it's an unboxing operation, so it won't do any implicit conversions like the ones you describe. Casting is sometimes confusing in C# if you don't know the details... Anyhow, because int != short, it will throw (unboxing fails). If you do object o = (short)5;, it will work, because then the types will match. It's not about the range, it's really about the type. – Greenhouse

Answer 5

Take the following example:

int one = 1;
MyEnum e = (MyEnum)one;

Maxima

Answer 6

I am using this piece of code to cast int to my enum:

if (typeof(YourEnum).IsEnumDefined(valueToCast))
    return (YourEnum)valueToCast;
else 
{
    // handle it here, if it is not defined
}

I find it the best solution.

Whitman

this is good. i was surprised there's not an exception when casting an invalid value to an int-backed enum. – Fake

This actually is not so different than the top-rated answer. That answer also discusses using Enum.IsDefined after you've casted the string to the Enum type. So even if the string was casted without error, Enum.IsDefined will still catch it – Compulsive

Answer 7

Below is a nice utility class for Enums

public static class EnumHelper
{
    public static int[] ToIntArray<T>(T[] value)
    {
        int[] result = new int[value.Length];
        for (int i = 0; i < value.Length; i++)
            result[i] = Convert.ToInt32(value[i]);
        return result;
    }

    public static T[] FromIntArray<T>(int[] value) 
    {
        T[] result = new T[value.Length];
        for (int i = 0; i < value.Length; i++)
            result[i] = (T)Enum.ToObject(typeof(T),value[i]);
        return result;
    }


    internal static T Parse<T>(string value, T defaultValue)
    {
        if (Enum.IsDefined(typeof(T), value))
            return (T) Enum.Parse(typeof (T), value);

        int num;
        if(int.TryParse(value,out num))
        {
            if (Enum.IsDefined(typeof(T), num))
                return (T)Enum.ToObject(typeof(T), num);
        }

        return defaultValue;
    }
}

Aryn

Answer 8

For numeric values, this is safer as it will return an object no matter what:

public static class EnumEx
{
    static public bool TryConvert<T>(int value, out T result)
    {
        result = default(T);
        bool success = Enum.IsDefined(typeof(T), value);
        if (success)
        {
            result = (T)Enum.ToObject(typeof(T), value);
        }
        return success;
    }
}

Fermata

You return default(T) when it's not defined. How is that helping to identify the undefined ones? – Klimesh

Answer 9

If you're ready for the 4.0 .NET Framework, there's a new Enum.TryParse() function that's very useful and plays well with the [Flags] attribute. See Enum.TryParse Method (String, TEnum%)

Twelvemo

That's useful when converting from a string. But not when converting from an int. – Opisthognathous

Answer 10

Sometimes you have an object to the MyEnum type. Like

var MyEnumType = typeof(MyEnum);

Then:

Enum.ToObject(typeof(MyEnum), 3)

Comras

Answer 11

If you have an integer that acts as a bitmask and could represent one or more values in a [Flags] enumeration, you can use this code to parse the individual flag values into a list:

for (var flagIterator = 0; flagIterator < 32; flagIterator++)
{
    // Determine the bit value (1,2,4,...,Int32.MinValue)
    int bitValue = 1 << flagIterator;

    // Check to see if the current flag exists in the bit mask
    if ((intValue & bitValue) != 0)
    {
        // If the current flag exists in the enumeration, then we can add that value to the list
        // if the enumeration has that flag defined
        if (Enum.IsDefined(typeof(MyEnum), bitValue))
            Console.WriteLine((MyEnum)bitValue);
    }
}

Note that this assumes that the underlying type of the enum is a signed 32-bit integer. If it were a different numerical type, you'd have to change the hardcoded 32 to reflect the bits in that type (or programatically derive it using Enum.GetUnderlyingType())

Preordain

Answer 12

This is an flags enumeration aware safe convert method:

public static bool TryConvertToEnum<T>(this int instance, out T result)
  where T: Enum
{
  var enumType = typeof (T);
  var success = Enum.IsDefined(enumType, instance);
  if (success)
  {
    result = (T)Enum.ToObject(enumType, instance);
  }
  else
  {
    result = default(T);
  }
  return success;
}

Girgenti

This can now be improved with C# 7.3 by constraining to Enum instead of struct, meaning we don't have to rely on the runtime check! – Oosperm

Answer 13

To convert a string to ENUM or int to ENUM constant we need to use Enum.Parse function. Here is a youtube video https://www.youtube.com/watch?v=4nhx4VwdRDk which actually demonstrate's with string and the same applies for int.

The code goes as shown below where "red" is the string and "MyColors" is the color ENUM which has the color constants.

MyColors EnumColors = (MyColors)Enum.Parse(typeof(MyColors), "Red");

Bolection

Answer 14

Slightly getting away from the original question, but I found an answer to Stack Overflow question Get int value from enum useful. Create a static class with public const int properties, allowing you to easily collect together a bunch of related int constants, and then not have to cast them to int when using them.

public static class Question
{
    public static readonly int Role = 2;
    public static readonly int ProjectFunding = 3;
    public static readonly int TotalEmployee = 4;
    public static readonly int NumberOfServers = 5;
    public static readonly int TopBusinessConcern = 6;
}

Obviously, some of the enum type functionality will be lost, but for storing a bunch of database id constants, it seems like a pretty tidy solution.

Gad

enums superseded the use of integer constants like this since they provide more type safety – Lorenzen

Paul, this is a method of collecting together related int constants (e.g. Database id constants) so they can be used directly without having to cast them to int every time they're used. Their type is integer, not for example, DatabaseIdsEnum. – Gad

There is at least one situation that I have found in which enum type safety can be unintentionally bypassed. – Concavity

But enums also make sure the values are all unique, something this approach is also lacking – Cloe

Answer 15

The following is a slightly better extension method:

public static string ToEnumString<TEnum>(this int enumValue)
{
    var enumString = enumValue.ToString();
    if (Enum.IsDefined(typeof(TEnum), enumValue))
    {
        enumString = ((TEnum) Enum.ToObject(typeof (TEnum), enumValue)).ToString();
    }
    return enumString;
}

Shayla

this is actually much better because if the int value is not a defined entry in the enum, you can use a else statement to set enumString to a default value. Thanks – Zalucki

Answer 16

This parses integers or strings to a target enum with partial matching in .NET 4.0 using generics like in Tawani's utility class. I am using it to convert command-line switch variables which may be incomplete. Since an enum cannot be null, you should logically provide a default value. It can be called like this:

var result = EnumParser<MyEnum>.Parse(valueToParse, MyEnum.FirstValue);

Here's the code:

using System;

public class EnumParser<T> where T : struct
{
    public static T Parse(int toParse, T defaultVal)
    {
        return Parse(toParse + "", defaultVal);
    }
    public static T Parse(string toParse, T defaultVal)
    {
        T enumVal = defaultVal;
        if (defaultVal is Enum && !String.IsNullOrEmpty(toParse))
        {
            int index;
            if (int.TryParse(toParse, out index))
            {
                Enum.TryParse(index + "", out enumVal);
            }
            else
            {
                if (!Enum.TryParse<T>(toParse + "", true, out enumVal))
                {
                    MatchPartialName(toParse, ref enumVal);
                }
            }
        }
        return enumVal;
    }

    public static void MatchPartialName(string toParse, ref T enumVal)
    {
        foreach (string member in enumVal.GetType().GetEnumNames())
        {
            if (member.ToLower().Contains(toParse.ToLower()))
            {
                if (Enum.TryParse<T>(member + "", out enumVal))
                {
                    break;
                }
            }
        }
    }
}

FYI: The question was about integers, which nobody mentioned will also explicitly convert in Enum.TryParse()

Compensable

Answer 17

From a string: (Enum.Parse is out of Date, use Enum.TryParse)

enum Importance
{}

Importance importance;

if (Enum.TryParse(value, out importance))
{
}

Argillaceous

The question specifically asks about integers. – Chagall

Will Yu please edit your answer to let everyone know Enum.TryParse will work on a string of the value or name of the enum (I couldn't resist) – Succinate

If value is not from enum that code will fire exception %( – Pinkiepinkish

Answer 18

You should build in some type matching relaxation to be more robust.

public static T ToEnum<T>(dynamic value)
{
    if (value == null)
    {
        // default value of an enum is the object that corresponds to
        // the default value of its underlying type
        // https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/default-values-table
        value = Activator.CreateInstance(Enum.GetUnderlyingType(typeof(T)));
    }
    else if (value is string name)
    {
        return (T)Enum.Parse(typeof(T), name);
    }

    return (T)Enum.ToObject(typeof(T),
             Convert.ChangeType(value, Enum.GetUnderlyingType(typeof(T))));
}

Test Case

[Flags]
public enum A : uint
{
    None  = 0, 
    X     = 1 < 0,
    Y     = 1 < 1
}

static void Main(string[] args)
{
    var value = EnumHelper.ToEnum<A>(7m);
    var x = value.HasFlag(A.X); // true
    var y = value.HasFlag(A.Y); // true

    var value2 = EnumHelper.ToEnum<A>("X");

    var value3 = EnumHelper.ToEnum<A>(null);

    Console.ReadKey();
}

Gust

Answer 19

For string, you can do the following:

var result = Enum.TryParse(typeof(MyEnum), yourString, out yourEnum) 

And make sure to check the result to determine if the conversion failed.

For int, you can do the following:

MyEnum someValue = (MyEnum)myIntValue;

Basset

works in case of a string not an int for example – Frap

Added case for int. – Basset

Answer 20

The easy and clear way for casting an int to enum in C#:

public class Program
{
    public enum Color : int
    {
        Blue   = 0,
        Black  = 1,
        Green  = 2,
        Gray   = 3,
        Yellow = 4
    }

    public static void Main(string[] args)
    {
        // From string
        Console.WriteLine((Color) Enum.Parse(typeof(Color), "Green"));

        // From int
        Console.WriteLine((Color)2);

        // From number you can also
        Console.WriteLine((Color)Enum.ToObject(typeof(Color), 2));
    }
}

Chattanooga

Answer 21

Here's an extension method that casts Int32 to Enum.

It honors bitwise flags even when the value is higher than the maximum possible. For example if you have an enum with possibilities 1, 2, and 4, but the int is 9, it understands that as 1 in absence of an 8. This lets you make data updates ahead of code updates.

   public static TEnum ToEnum<TEnum>(this int val) where TEnum : struct, IComparable, IFormattable, IConvertible
    {
        if (!typeof(TEnum).IsEnum)
        {
            return default(TEnum);
        }

        if (Enum.IsDefined(typeof(TEnum), val))
        {//if a straightforward single value, return that
            return (TEnum)Enum.ToObject(typeof(TEnum), val);
        }

        var candidates = Enum
            .GetValues(typeof(TEnum))
            .Cast<int>()
            .ToList();

        var isBitwise = candidates
            .Select((n, i) => {
                if (i < 2) return n == 0 || n == 1;
                return n / 2 == candidates[i - 1];
            })
            .All(y => y);

        var maxPossible = candidates.Sum();

        if (
            Enum.TryParse(val.ToString(), out TEnum asEnum)
            && (val <= maxPossible || !isBitwise)
        ){//if it can be parsed as a bitwise enum with multiple flags,
          //or is not bitwise, return the result of TryParse
            return asEnum;
        }

        //If the value is higher than all possible combinations,
        //remove the high imaginary values not accounted for in the enum
        var excess = Enumerable
            .Range(0, 32)
            .Select(n => (int)Math.Pow(2, n))
            .Where(n => n <= val && n > 0 && !candidates.Contains(n))
            .Sum();

        return Enum.TryParse((val - excess).ToString(), out asEnum) ? asEnum : default(TEnum);
    }

Geoffrey

Answer 22

In my case, I needed to return the enum from a WCF service. I also needed a friendly name, not just the enum.ToString().

Here's my WCF Class.

[DataContract]
public class EnumMember
{
    [DataMember]
    public string Description { get; set; }

    [DataMember]
    public int Value { get; set; }

    public static List<EnumMember> ConvertToList<T>()
    {
        Type type = typeof(T);

        if (!type.IsEnum)
        {
            throw new ArgumentException("T must be of type enumeration.");
        }

        var members = new List<EnumMember>();

        foreach (string item in System.Enum.GetNames(type))
        {
            var enumType = System.Enum.Parse(type, item);

            members.Add(
                new EnumMember() { Description = enumType.GetDescriptionValue(), Value = ((IConvertible)enumType).ToInt32(null) });
        }

        return members;
    }
}

Here's the Extension method that gets the Description from the Enum.

    public static string GetDescriptionValue<T>(this T source)
    {
        FieldInfo fileInfo = source.GetType().GetField(source.ToString());
        DescriptionAttribute[] attributes = (DescriptionAttribute[])fileInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);            

        if (attributes != null && attributes.Length > 0)
        {
            return attributes[0].Description;
        }
        else
        {
            return source.ToString();
        }
    }

Implementation:

return EnumMember.ConvertToList<YourType>();

Clein

Answer 23

It can help you to convert any input data to user desired enum. Suppose you have an enum like below which by default int. Please add a Default value at first of your enum. Which is used at helpers medthod when there is no match found with input value.

public enum FriendType  
{
    Default,
    Audio,
    Video,
    Image
}

public static class EnumHelper<T>
{
    public static T ConvertToEnum(dynamic value)
    {
        var result = default(T);
        var tempType = 0;

        //see Note below
        if (value != null &&
            int.TryParse(value.ToString(), out  tempType) && 
            Enum.IsDefined(typeof(T), tempType))
        {
            result = (T)Enum.ToObject(typeof(T), tempType); 
        }
        return result;
    }
}

N.B: Here I try to parse value into int, because enum is by default int If you define enum like this which is byte type.

public enum MediaType : byte
{
    Default,
    Audio,
    Video,
    Image
} 

You need to change parsing at helper method from

int.TryParse(value.ToString(), out  tempType)

to

byte.TryParse(value.ToString(), out tempType)

I check my method for following inputs

EnumHelper<FriendType>.ConvertToEnum(null);
EnumHelper<FriendType>.ConvertToEnum("");
EnumHelper<FriendType>.ConvertToEnum("-1");
EnumHelper<FriendType>.ConvertToEnum("6");
EnumHelper<FriendType>.ConvertToEnum("");
EnumHelper<FriendType>.ConvertToEnum("2");
EnumHelper<FriendType>.ConvertToEnum(-1);
EnumHelper<FriendType>.ConvertToEnum(0);
EnumHelper<FriendType>.ConvertToEnum(1);
EnumHelper<FriendType>.ConvertToEnum(9);

sorry for my english

Divertissement

Answer 24

Different ways to cast to and from Enum

enum orientation : byte
{
 north = 1,
 south = 2,
 east = 3,
 west = 4
}

class Program
{
  static void Main(string[] args)
  {
    orientation myDirection = orientation.north;
    Console.WriteLine(“myDirection = {0}”, myDirection); //output myDirection =north
    Console.WriteLine((byte)myDirection); //output 1

    string strDir = Convert.ToString(myDirection);
        Console.WriteLine(strDir); //output north

    string myString = “north”; //to convert string to Enum
    myDirection = (orientation)Enum.Parse(typeof(orientation),myString);


 }
}

Rosinweed

Answer 25

I don't know anymore where I get the part of this enum extension, but it is from stackoverflow. I am sorry for this! But I took this one and modified it for enums with Flags. For enums with Flags I did this:

  public static class Enum<T> where T : struct
  {
     private static readonly IEnumerable<T> All = Enum.GetValues(typeof (T)).Cast<T>();
     private static readonly Dictionary<int, T> Values = All.ToDictionary(k => Convert.ToInt32(k));

     public static T? CastOrNull(int value)
     {
        T foundValue;
        if (Values.TryGetValue(value, out foundValue))
        {
           return foundValue;
        }

        // For enums with Flags-Attribut.
        try
        {
           bool isFlag = typeof(T).GetCustomAttributes(typeof(FlagsAttribute), false).Length > 0;
           if (isFlag)
           {
              int existingIntValue = 0;

              foreach (T t in Enum.GetValues(typeof(T)))
              {
                 if ((value & Convert.ToInt32(t)) > 0)
                 {
                    existingIntValue |= Convert.ToInt32(t);
                 }
              }
              if (existingIntValue == 0)
              {
                 return null;
              }

              return (T)(Enum.Parse(typeof(T), existingIntValue.ToString(), true));
           }
        }
        catch (Exception)
        {
           return null;
        }
        return null;
     }
  }

Example:

[Flags]
public enum PetType
{
  None = 0, Dog = 1, Cat = 2, Fish = 4, Bird = 8, Reptile = 16, Other = 32
};

integer values 
1=Dog;
13= Dog | Fish | Bird;
96= Other;
128= Null;

Seventeen

Answer 26

You simply use Explicit conversion Cast int to enum or enum to int

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine((int)Number.three); //Output=3

        Console.WriteLine((Number)3);// Outout three
        Console.Read();
    }

    public enum Number
    {
        Zero = 0,
        One = 1,
        Two = 2,
        three = 3
    }
}

Whaleback

Answer 27

I prefer a short way using a nullable enum type variable.

var enumValue = (MyEnum?)enumInt;

if (!enumValue.HasValue)
{
    throw new ArgumentException(nameof(enumValue));
}

Edifice

I think this does not work. The cast succeeds, and returns a non-null value, even if the integer is out of range. – Dawndawna

It really does not work now. Which is very strange, because I think I used to use this approach. Could it be, that some next version of .NET has broken this functionality? – Edifice

Answer 28

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace SamplePrograme
{
    public class Program
    {
        public enum Suit : int
        {
            Spades = 0,
            Hearts = 1,
            Clubs = 2,
            Diamonds = 3
        }

        public static void Main(string[] args)
        {
            //from string
            Console.WriteLine((Suit) Enum.Parse(typeof(Suit), "Clubs"));

            //from int
            Console.WriteLine((Suit)1);

            //From number you can also
            Console.WriteLine((Suit)Enum.ToObject(typeof(Suit) ,1));
        }
    }
}

Structural

Answer 29

You just do like below:

int intToCast = 1;
TargetEnum f = (TargetEnum) intToCast ;

To make sure that you only cast the right values ​​and that you can throw an exception otherwise:

int intToCast = 1;
if (Enum.IsDefined(typeof(TargetEnum), intToCast ))
{
    TargetEnum target = (TargetEnum)intToCast ;
}
else
{
   // Throw your exception.
}

Note that using IsDefined is costly and even more than just casting, so it depends on your implementation to decide to use it or not.

Fermin

Answer 30

You can use an extension method.

public static class Extensions
{

    public static T ToEnum<T>(this string data) where T : struct
    {
        if (!Enum.TryParse(data, true, out T enumVariable))
        {
            if (Enum.IsDefined(typeof(T), enumVariable))
            {
                return enumVariable;
            }
        }

        return default;
    }

    public static T ToEnum<T>(this int data) where T : struct
    {
        return (T)Enum.ToObject(typeof(T), data);
    }
}

Use it like the below code:

Enum:

public enum DaysOfWeeks
{
    Monday = 1,
    Tuesday = 2,
    Wednesday = 3,
    Thursday = 4,
    Friday = 5,
    Saturday = 6,
    Sunday = 7,
}

Usage:

 string Monday = "Mon";
 int Wednesday = 3;
 var Mon = Monday.ToEnum<DaysOfWeeks>();
 var Wed = Wednesday.ToEnum<DaysOfWeeks>();

Disembowel

Answer 31

Simple you can cast int to enum

 public enum DaysOfWeeks
    {
        Monday = 1,
        Tuesday = 2,
        Wednesday = 3,
        Thursday = 4,
        Friday = 5,
        Saturday = 6,
        Sunday = 7,
    } 

    var day= (DaysOfWeeks)5;
    Console.WriteLine("Day is : {0}", day);
    Console.ReadLine();

Bascio

If the cast worked, you wouldn't be able to store it as an int. – Nisus

Please try to understand int to Enum I think is above answer to help you. – Bascio

Answer 32

I need two instructions:

YourEnum possibleEnum = (YourEnum)value; // There isn't any guarantee that it is part of the enum
if (Enum.IsDefined(typeof(YourEnum), possibleEnum))
{
    // Value exists in YourEnum
}

Diamante