How to convert any int into any generic Enum in C#?

Question

Because Enums aren't guaranteed to be of type int...

public enum ExampleEnum : int / ulong / whatever

You cannot do this with enums:

int i = (int)exampleEnum;

However in my case, while I don't know the exact 'type of enum' being used, I can guarantee that it will be a "int type" of enum.

So I can do this:

int i = Convert.ToInt32(exampleEnum);

Cool. Here's the problem: I don't know of a way to do the inverse (which I need to do), as:

Enum exampleEnum = (Enum)exampleEnum;

has error:

Cannot cast expression of type 'int' to type 'Enum'

And I cannot find an inverse of Convert.ToInt32(Enum enum)

That is the question, if you think more detail on what I'm trying to do is useful, I can provide you with it. But in a nutshell I am creating a generic GUI method that takes in any type of Enum:

public static int EditorPrefEnumField(string label, Enum defaultValue, string editorPrefString)

and getting it to work (the way I want) involves converting the Enum to and from an int.

`Enum` is a class that is the base for all `enum` types. It's a special type, similar to `ValueType`. You need to cast as the specific type you want rather than just as `Enum`, as demonstrated in the comment above. — jmcilhinney, Nov 30 '22 at 01:11
https://stackoverflow.com/questions/1682231/how-do-valuetypes-derive-from-object-referencetype-and-still-be-valuetypes — marsze, Nov 30 '22 at 01:43

NineBerry · Accepted Answer · 2022-11-30T02:20:45.117

4

You can use Enum.ToObject() method. You need to specify the actual enum type for that. Here is a generic method to encapsulate Enum.ToObject()

public enum TestEnum : int 
{
    A=1, B=2, C=3
};

public T GetEnumFromInt<T>(int value) where T : Enum
{
    return (T)Enum.ToObject(typeof(T), value);
}

private void button1_Click(object sender, EventArgs e) 
{
    Enum value = GetEnumFromInt<TestEnum>(2);
    MessageBox.Show(value.ToString()); // Displays "B" 
}

You need to specify the concrete type of Enum you want because Enum is an abstract type and one cannot create instances of abstract types.

edited Nov 30 '22 at 02:20

answered Nov 30 '22 at 01:36

NineBerry

26,306
3
62
93

This is correct! This is basically the code I ended up using: 'Enum exampleEnum = (Enum)Enum.ToObject(enumType, intValue);' – danglingPointer Nov 30 '22 at 03:06

Jeremy Thompson · Answer 2 · 2022-11-30T02:12:28.110

Take this code where I store an error code as an Int:

public class CommonError
{
   public int Code { get; set; }

   public CommonError FromErrorCode(Enum code, string description = "")
   {
        Code = (int)Enum.Parse(code.GetType(), code.ToString());                        
        return this;
   }
}

Yet what I'm doing when I call it is parsing in different Enums:

new CommonError().FromErrorCode((int)GeneralErrorCodes.SYSTEM_BASE_ERROR);

Cool. Here's the problem: I don't know of a way to do the inverse (which I need to do)

To do the reverse of this you need the Enum Type, eg:

Enum.GetNames(typeof(AnEmumType))

Enum.GetValues(typeof(AnEmumType)).ToList();

How to convert any int into any generic Enum in C#?

2 Answers2