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C# Enum with Char Valued Items

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3 May 2010CPOL3 min read 115.7K   9   36
How to use a char as a value for enum items, and why

Introduction

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?

Background

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:

C#
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:

C#
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:

C#
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

C#
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()).

History

  • 3rd May, 2010: Initial post

License

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


Written By
Software Developer (Senior) Truphone
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Comments and Discussions

 
QuestionExample, how to use it Pin
Squartol5-Jan-17 5:09
Squartol5-Jan-17 5:09 
GeneralMy vote of 2 Pin
nguyen1908875-Jun-12 21:23
nguyen1908875-Jun-12 21:23 
AnswerOne way to use Pin
Anamotiris4-May-10 22:24
Anamotiris4-May-10 22:24 
GeneralRe: One way to use Pin
ricmrodrigues4-May-10 22:37
ricmrodrigues4-May-10 22:37 
GeneralMy vote of 2 Pin
grif4-May-10 4:21
grif4-May-10 4:21 
GeneralRe: My vote of 2 Pin
ricmrodrigues4-May-10 4:50
ricmrodrigues4-May-10 4:50 
GeneralStrange Pin
JP van Mackelenbergh3-May-10 18:46
JP van Mackelenbergh3-May-10 18:46 
GeneralRe: Strange Pin
ricmrodrigues4-May-10 2:58
ricmrodrigues4-May-10 2:58 
GeneralRe: Strange Pin
PIEBALDconsult4-May-10 3:00
mvePIEBALDconsult4-May-10 3:00 
GeneralRe: Strange Pin
ricmrodrigues4-May-10 3:16
ricmrodrigues4-May-10 3:16 
GeneralMore thoughts Pin
PIEBALDconsult3-May-10 15:41
mvePIEBALDconsult3-May-10 15:41 
GeneralRe: More thoughts Pin
ricmrodrigues4-May-10 2:59
ricmrodrigues4-May-10 2:59 
GeneralRe: More thoughts Pin
PIEBALDconsult4-May-10 3:45
mvePIEBALDconsult4-May-10 3:45 
GeneralRe: More thoughts Pin
ricmrodrigues4-May-10 3:55
ricmrodrigues4-May-10 3:55 
GeneralRe: More thoughts Pin
PIEBALDconsult4-May-10 3:59
mvePIEBALDconsult4-May-10 3:59 
GeneralRe: More thoughts Pin
ricmrodrigues4-May-10 4:23
ricmrodrigues4-May-10 4:23 
GeneralRe: More thoughts Pin
PIEBALDconsult4-May-10 11:03
mvePIEBALDconsult4-May-10 11:03 
GeneralRe: More thoughts Pin
ricmrodrigues4-May-10 11:33
ricmrodrigues4-May-10 11:33 
GeneralRe: More thoughts Pin
PIEBALDconsult4-May-10 12:47
mvePIEBALDconsult4-May-10 12:47 
GeneralRe: More thoughts Pin
ricmrodrigues4-May-10 12:55
ricmrodrigues4-May-10 12:55 
GeneralThoughts Pin
PIEBALDconsult3-May-10 4:58
mvePIEBALDconsult3-May-10 4:58 
GeneralRe: Thoughts Pin
ricmrodrigues3-May-10 7:15
ricmrodrigues3-May-10 7:15 
0) Yes, and the question here is solving the problem, if you can use an int, there's not a problem to start with Smile | :)
1) I know the enum attributes..but it's just not the same, it's not the absolute value of the enum item.
2) Think about it, from the user point of view, it's the most obvious name, yes I could use stringValue, but it's the string I want translated to my enum, so, if the possibility of naming my parameter 'string' exists, I don't see why I shouldn't use it, nor why it's a poor practice, and it's not even a constructive critic.
GeneralRe: Thoughts Pin
PIEBALDconsult3-May-10 12:57
mvePIEBALDconsult3-May-10 12:57 
GeneralRe: Thoughts Pin
ricmrodrigues3-May-10 14:16
ricmrodrigues3-May-10 14:16 
GeneralAlternate solution Pin
derekschwechel3-May-10 3:54
derekschwechel3-May-10 3:54 

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