How do I define a C# enum that includes integers as values?

Question

I'm designing an application that requires a "location" field. The values for the location are "3241", "4112", "ND" and "TRAVEL", and I am trying to set up an enum that includes those values.

I started with

    enum projectLocation {3241,4112,ND,TRAVEL};

but the values 3241 and 4112 indicated a syntax error--identifier expected--for the first value in the enum. If I understand enum correctly, that's because the above statement is looking for the value for the enum's integer indeces of 3241 and 4112. Is this a correct assumption?

I tried overriding that with the following

    enum projectLocation {3241=0,4112,ND,TRAVEL};

and

    enum projectLocation {3241=0,4112=1,ND=2,TRAVEL=3};

but I'm still getting the same syntax error on the 3241 value. Interestingly though, on both of these statements, there is NO syntax error on 4112, but I get can't find the namespace or name ND and ...TRAVEL

It makes sense that enum will not allow a mix of strings and integers, and I have two other enums that work fine and are only lists of string values, corroborating that theory. Is there a way to force enum to accept the numeric values as strings? I've not been able to find any references in MSDNs C# documentation.

Answer 1

Enums are called as named constants, so basically you give a name for some constant. Names are "identifiers" in c#, where identifier can contain numbers but first character cannot be a number.

You can add _ before that to fix this error.

enum projectLocation 
{
    _3241=0,
    _4112=1,
    ND=2,
    TRAVEL=3
}

Also note the Fields, Properties Methods or whatever falls under this identifier rule mentioned above.

Answer 2

You can't do it exactly like you're trying to. Here's an alternative:

enum projectLocation {
    L3241=3241,
    L4112=4112,
    ND=2,
    TRAVEL=3
}

Starting them with a letter makes them valid enum identifiers, and setting their value equal to their number lets you do things like (projectLocation)3241 and get the expected L3241 value.

If you need the values to be 3241 and 4112 when serialized, include the proper attribute for your serialization approach, e.g. with Json.NET:

enum projectLocation {
    [JsonProperty("3241")]
    L3241=3241,
    [JsonProperty("4112")]
    L4112=4112,
    ND=2,
    TRAVEL=3
}

Answer 3

You would need to do something like this:

enum projectLocation { v3241, v4112, ND, TRAVEL };

or:

enum projectLocation { _3241, _4112, ND, TRAVEL };

My preference would be the use of the underscore.

Answer 4

C# does not allow the first character of member names to start with a number. Consider using the @ character as a prefix, or some other character that conveys a meaning useful to a reader of the code as a number in isolation may not be very intuitive to a reader not familiar with the significance of 3241 in your context.