C# using numbers in an enum

Question

This is a valid enum

public enum myEnum {   a= 1,   b= 2,   c= 3,   d= 4,   e= 5,   f= 6,   g= 7,   h= 0xff }; 

But this is not

public enum myEnum {   1a = 1,   2a = 2,   3a = 3, }; 

Is there a way I can use an number in a enum? I already have code that would populate dropdowns from enums so it would be quite handy

Answer 1

No, there isn't. C# does not allow identifiers to start with a digit.

Application usability note: In your application you should not display code identifiers to the end-user anyway. Think of translating individual enumeration items into user-friendly displayable texts. Sooner or later you'll have to extend the enum with an item whose identifier won't be in a form displayable to the user.

UPDATE: Note that the way for attaching displayable texts to enumeration items is being discusses, for example, here.

Answer 2

No identifier at all in C# may begin with a number (for lexical/parsing reasons). Consider adding a [Description] attribute to your enum values:

public enum myEnum {     [Description("1A")]     OneA = 1,     [Description("2A")]     TwoA = 2,     [Description("3A")]     ThreeA = 3, }; 

Then you can get the description from an enum value like this:

((DescriptionAttribute)Attribute.GetCustomAttribute(     typeof(myEnum).GetFields(BindingFlags.Public | BindingFlags.Static)         .Single(x => (myEnum)x.GetValue(null) == enumValue),         typeof(DescriptionAttribute))).Description 

Based on XSA's comment below, I wanted to expand on how one could make this more readable. Most simply, you could just create a static (extension) method:

public static string GetDescription(this Enum value) {     return ((DescriptionAttribute)Attribute.GetCustomAttribute(         value.GetType().GetFields(BindingFlags.Public | BindingFlags.Static)             .Single(x => x.GetValue(null).Equals(value)),         typeof(DescriptionAttribute)))?.Description ?? value.ToString(); } 

It's up to you whether you want to make it an extension method, and in the implementation above, I've made it fallback to the enum's normal name if no [DescriptionAttribute] has been provided.

Now you can get the description for an enum value via:

myEnum.OneA.GetDescription()