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C# Enum with Char Valued Items

, 3 May 2010 CPOL
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How to use a char as a value for enum items, and why


Focusing on the subject, what am I going to write about the Enum type?

  • Can we assign an Enum item to anything that's not of the int type?
  • Why would I even bother thinking about this?
  • How can I handle converting something to Enum and back to something again?


This all started when I had a database field with a char, and needed to have a strongly typed way of handling it in my C# code, and then I figured it out, it's possible.

Using the Code

First of all, YES, we can assign an Enum to something else, a char!
And how?
Just like you're thinking about it, yes:

public Enum myEnum
  value1 = 'a',
  value2 = 'b'

And why would I think about this?

Have you ever had to write some DAL code or mapping an existing database to an ORM, say Entity Framework, and you had fields which contained, for some particular reason, a list of controlled chars, which aren't related to any other table, like a field called State which had the possible values, 'R' for Ready, 'P' for Pending and 'C' for Cancelled, and you want to have some nice and type-safe way of manipulating this field on code and at the same time a generic way, which can be used everywhere, well, you can do it using those chars on an Enum type:

public Enum State
  Ready = 'R',
  Pending = 'P',
  Cancelled = 'C'

And how can I handle this? I'll sure try to do a State.ToString() and it will return a number to me, why??

Because, actually, you can't have an Enum item with an associated char, but .NET lets you do this, and internally it converts your char to its equivalent int representation (ASCII).

So, now you're thinking, so now what? How can I get my char??
Simple enough, just cast the Enum item to a char first, and then you get its char representation:

string type = ((char)StateEnum).ToString();  

This way, you can extract the char from the int, and get your value!
This is for persisting your data to your datasource (convert the Enum item to the value that your datasource is expecting, the char).

But now, you need to convert your char to the corresponding Enum item, when you get your char field from your datasource, right?
How can this be done?
Well I've coded a method to do that, with generics, let's see:

Code at pastebin

public static T ToEnum< T >(string @string)   
   if (string.IsNullOrEmpty(@string))
    throw new ArgumentException("Argument null or empty");
   if (@string.Length > 1)
    throw new ArgumentException("Argument length greater than one");
   return (T)Enum.ToObject(typeof(T), @string[0]);

So what you do here is accept a string (could be a char, it's just to make it simpler, since many ORMs map a char on the database to string, not char), and then you check your parameters, if they're not null, and if the length of the string is one (which matches a char), and then, you use the ToObject method from the Enum type, that accepts the return type you want to get, and the corresponding Enum item value (int or char) to convert to.

And that's it, you can use chars with an Enum object, isn't this awesome? When I got around this, I just thought about the numerous times that I needed it...

Hope this helps you as much as it has helped me.

Points of Interest

The key discovery was the conversion from the enum to char, you need to cast it to char first, and only then you can have your char value, because since the .NET Framework thinks it's an int, you must convert it to char (so it translates the int to the equivalent char on the ASCII table, like the old method chr()).


  • 3rd May, 2010: Initial post


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

GeneralMy vote of 2 Pinmembernguyen1908875-Jun-12 22:23 
AnswerOne way to use PinmemberAnamotiris4-May-10 23:24 
GeneralRe: One way to use Pinmemberricrodrigues4-May-10 23:37 
GeneralMy vote of 2 Pinmembergrif4-May-10 5:21 
GeneralRe: My vote of 2 Pinmemberricrodrigues4-May-10 5:50 
GeneralStrange PinmemberJuicy3-May-10 19:46 
GeneralRe: Strange Pinmemberricrodrigues4-May-10 3:58 
GeneralRe: Strange PinmvpPIEBALDconsult4-May-10 4:00 
GeneralRe: Strange Pinmemberricrodrigues4-May-10 4:16 
GeneralMore thoughts PinmvpPIEBALDconsult3-May-10 16:41 
GeneralRe: More thoughts Pinmemberricrodrigues4-May-10 3:59 
GeneralRe: More thoughts PinmvpPIEBALDconsult4-May-10 4:45 
GeneralRe: More thoughts Pinmemberricrodrigues4-May-10 4:55 
GeneralRe: More thoughts PinmvpPIEBALDconsult4-May-10 4:59 
GeneralRe: More thoughts Pinmemberricrodrigues4-May-10 5:23 
GeneralRe: More thoughts PinmvpPIEBALDconsult4-May-10 12:03 
GeneralRe: More thoughts Pinmemberricrodrigues4-May-10 12:33 
GeneralRe: More thoughts PinmvpPIEBALDconsult4-May-10 13:47 
GeneralRe: More thoughts Pinmemberricrodrigues4-May-10 13:55 
GeneralThoughts PinmvpPIEBALDconsult3-May-10 5:58 
GeneralRe: Thoughts Pinmemberricrodrigues3-May-10 8:15 
GeneralRe: Thoughts PinmvpPIEBALDconsult3-May-10 13:57 
GeneralRe: Thoughts Pinmemberricrodrigues3-May-10 15:16 
GeneralAlternate solution Pinmemberderekschwechel3-May-10 4:54 
GeneralRe: Alternate solution Pinmemberricrodrigues3-May-10 5:28 
GeneralRe: Alternate solution Pinmemberderekschwechel3-May-10 16:27 
GeneralRe: Alternate solution Pinmemberricrodrigues4-May-10 4:14 
GeneralRe: Alternate solution PinmemberdzCepheus4-May-10 5:34 
State.Ready could return a statically-defined instance of the State struct, for which there can be a conversion operator defined to convert to and from char. That would allow you to maintain the semantics of the variable, while still allowing you to store its value in some other native format. And this way, you're not limited to integral types (of which char is ultimately one) - you could use strings, doubles, whatever your data store requires.
PS: This is what part of the alphabet would look like if the letters Q and R were removed.

GeneralRe: Alternate solution Pinmemberricrodrigues4-May-10 5:47 
GeneralRe: Alternate solution PinmemberdzCepheus4-May-10 5:58 
GeneralRe: Alternate solution Pinmemberricrodrigues4-May-10 6:30 
GeneralRe: Alternate solution PinmemberdzCepheus4-May-10 9:21 
GeneralRe: Alternate solution Pinmemberricrodrigues4-May-10 9:33 
Generaltoo complex solution ... Pinmembergmt523-May-10 3:07 
GeneralRe: too complex solution ... Pinmemberricrodrigues3-May-10 4:30 

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