How to define an enum with string value

Question

I am trying to define an Enum and add valid common separators which used in CSV or similar files  Then I am going to bind it to a ComboBox as a data source so whenever I add or remove from the Enum definition  I would not need to change anything in the combo box   The problem is how can I define enum with string representation  something like   public enum SeparatorChars Comma        Tab     t   Space

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For a simple enum of string values  or any other type    public static class MyEnumClass       public const string          MyValue1    My value 1           MyValue2    My value 2       Usage  string MyValue   MyEnumClass MyValue1

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We can t define enumeration as string type  The approved types for an enum are byte  sbyte  short  ushort  int  uint  long  or ulong   If you need more details on enumeration please follow below link that link will help you to understand enumeration  Enumeration   narendras1414

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You can t  because enum can only be based on a primitive numeric type  You could try using a Dictionary instead   Dictionary lt String  char gt  separators   new Dictionary lt string  char gt          Comma                Tab      t           Space                Alternatively  you could use a Dictionary lt Separator  char gt  or Dictionary lt Separator  string gt  where Separator is a normal enum   enum Separator       Comma      Tab      Space     which would be a bit more pleasant than handling the strings directly

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I created a base class for creating string-valued enums in  NET  It is just one C  file that you can copy  amp  paste into your projects  or install via NuGet package named StringEnum   Usage       lt completionlist cref  HexColor   gt   class HexColor   StringEnum lt HexColor gt        public static readonly HexColor Blue   New   FF0000        public static readonly HexColor Green   New   00FF00        public static readonly HexColor Red   New   000FF        Features   Your StringEnum looks somewhat similar to a regular enum           Static Parse Method     HexColor Parse   FF0000        gt  HexColor Red     HexColor Parse   ff0000   caseSensitive  false       gt  HexColor Red     HexColor Parse  invalid        gt  throws InvalidOperationException         Static TryParse method      HexColor TryParse   FF0000        gt  HexColor Red     HexColor TryParse   ff0000   caseSensitive  false       gt  HexColor Red     HexColor TryParse  invalid        gt  null         Parse and TryParse returns the preexistent instances     object ReferenceEquals HexColor Parse   FF0000    HexColor Red       gt  true         Conversion from your  StringEnum  to  string      string myString1   HexColor Red ToString         gt    FF0000      string myString2   HexColor Red       gt    FF0000   implicit cast     Intellisense will suggest the enum name if the class is annotated with the xml comment  lt completitionlist gt    Works in both C  and VB   i e      Instalation  Either    Install latest StringEnum NuGet package  which is based on  Net Standard 1 0 so it runs on  Net Core    1 0   Net Framework    4 5  Mono    4 6  etc  Or paste the following StringEnum base class to your project   latest version        public abstract class StringEnum lt T gt    IEquatable lt T gt  where T   StringEnum lt T gt   new                 protected string Value          private static IList lt T gt  valueList   new List lt T gt             protected static T New string value                        if  value    null                  return null     the null-valued instance is null               var result   new T     Value   value                valueList Add result               return result                     public static implicit operator string StringEnum lt T gt  enumValue    gt  enumValue Value          public override string ToString     gt  Value           public static bool operator    StringEnum lt T gt  o1  StringEnum lt T gt  o2    gt  o1  Value    o2  Value          public static bool operator    StringEnum lt T gt  o1  StringEnum lt T gt  o2    gt  o1  Value    o2  Value           public override bool Equals object other    gt  this Value Equals  other as T   Value     other as string            bool IEquatable lt T gt  Equals T other    gt  this Value Equals other Value           public override int GetHashCode     gt  Value GetHashCode                  lt summary gt              Parse the  lt paramref name  value   gt  specified and returns a valid  lt typeparamref name  T   gt  or else throws InvalidOperationException               lt  summary gt               lt param name  value  gt The string value representad by an instance of  lt typeparamref name  T   gt   Matches by string value  not by the member name  lt  param gt               lt param name  caseSensitive  gt If true  the strings must match case sensitivity  lt  param gt          public static T Parse string value  bool caseSensitive   false                        var result   TryParse value  caseSensitive               if  result    null                  throw new InvalidOperationException  value    null    null        value          is not a valid  typeof T  Name                  return result                          lt summary gt              Parse the  lt paramref name  value   gt  specified and returns a valid  lt typeparamref name  T   gt  or else returns null               lt  summary gt               lt param name  value  gt The string value representad by an instance of  lt typeparamref name  T   gt   Matches by string value  not by the member name  lt  param gt               lt param name  caseSensitive  gt If true  the strings must match case sensitivity  lt  param gt          public static T TryParse string value  bool caseSensitive   false                        if  value    null  return null              if  valueList Count    0  System Runtime CompilerServices RuntimeHelpers RunClassConstructor typeof T  TypeHandle      force static fields initialization             var field   valueList FirstOrDefault f   gt  f Value Equals value                      caseSensitive   StringComparison Ordinal                                     StringComparison OrdinalIgnoreCase                   Not using InvariantCulture because it s only supported in NETStandard  gt   2 0              if  field    null                  return null               return field                     For Newtonsoft Json serialization support  copy this extended version instead  StringEnum cs   I realized after the fact that this code is similar to Ben s answer  I sincerely wrote it from scratch  However I think it has a few extras  like the  lt completitionlist gt  hack  the resulting class looks more like an Enum  no use of reflection on Parse    the NuGet package and repo where I will hopefully address incoming issues and feedback

User · Answer

You can t - enum values have to be integral values  You can either use attributes to associate a string value with each enum value  or in this case if every separator is a single character you could just use the char value   enum Separator       Comma            Tab     t       Space            EDIT  Just to clarify  you can t make char the underlying type of the enum  but you can use char constants to assign the integral value corresponding to each enum value  The underlying type of the above enum is int    Then an extension method if you need one   public string ToSeparatorString this Separator separator           TODO  validation     return   char  separator  ToString

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Enumaration Class    public sealed class GenericDateTimeFormatType                public static readonly GenericDateTimeFormatType Format1   new GenericDateTimeFormatType  dd-MM-YYYY            public static readonly GenericDateTimeFormatType Format2   new GenericDateTimeFormatType  dd-MMM-YYYY             private GenericDateTimeFormatType string Format                         Value   Format                     public string  Value   get  private set               Enumaration Consuption   public static void Main            Country A   new Country            A DefaultDateFormat   GenericDateTimeFormatType Format1         Console ReadLine

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You can achieve it but will required bit of work    Define an attribute class which will contain the string value for enum  Define an extension method which will return back the value from the attribute  Eg  GetStringValue this Enum value  will return  attribute value  Then you can define the enum like this       public enum Test   int        StringValue  a        Foo   1       StringValue  b        Something   2               To get back the value from Attrinbute Test Foo GetStringValue      Refer   Enum With String Values In C

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It works for me        public class ShapeTypes               private ShapeTypes               public static string OVAL                       get                               return  ov                             private set                        public static string SQUARE                       get                               return  sq                             private set                        public static string RECTANGLE                       get                               return  rec                             private set

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While it is really not possible to use a char or a string as the base for an enum  i think this is not what you really like to do   Like you mentioned you d like to have an enum of possibilities and show a string representation of this within a combo box  If the user selects one of these string representations you d like to get out the corresponding enum  And this is possible   First we have to link some string to an enum value  This can be done by using the DescriptionAttribute like it is described here or here   Now you need to create a list of enum values and corresponding descriptions  This can be done by using the following method        lt summary gt      Creates an List with all keys and values of a given Enum class      lt  summary gt       lt typeparam name  T  gt Must be derived from class Enum  lt  typeparam gt       lt returns gt A list of KeyValuePair amp lt Enum  string amp gt  with all available     names and values of the given Enum  lt  returns gt  public static IList lt KeyValuePair lt T  string gt  gt  ToList lt T gt    where T   struct       var type   typeof T        if   type IsEnum                throw new ArgumentException  T must be an enum               return  IList lt KeyValuePair lt T  string gt  gt               Enum GetValues type                   OfType lt T gt                     Select e   gt                                        var asEnum    Enum Convert ChangeType e  typeof Enum                        return new KeyValuePair lt T  string gt  e  asEnum Description                                         ToArray        Now you ll have a list of key value pairs of all enums and their description  So let s simply assign this as a data source for a combo box   var comboBox   new ComboBox    comboBox ValueMember    Key  comboBox DisplayMember    Value   comboBox DataSource   EnumUtilities ToList lt Separator gt      comboBox SelectedIndexChanged     sender  e    gt        var selectedEnum    Separator comboBox SelectedValue      MessageBox Show selectedEnum ToString         The user sees all the string representations of the enum and within your code you ll get the desired enum value

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Maybe it s too late  but here it goes   We can use the attribute EnumMember to manage Enum values   public enum EUnitOfMeasure        EnumMember Value    KM        Kilometer       EnumMember Value    MI        Miles     This way the result value for EUnitOfMeasure will be KM or MI  This also can be seen in Andrew Whitaker answer

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It is kind of late for answer  but maybe it helps someone in future  I found it easier to use struct for this kind of problem    Following sample is copy pasted part from MS code   namespace System IdentityModel Tokens Jwt                 Summary             List of registered claims from different sources http   tools ietf org html rfc7519 section-4            http   openid net specs openid-connect-core-1 0 html IDToken     public struct JwtRegisteredClaimNames                             Summary                 http   tools ietf org html rfc7519 section-4         public const string Actort    actort                         Summary                 http   tools ietf org html rfc7519 section-4         public const string Typ    typ                         Summary                 http   tools ietf org html rfc7519 section-4         public const string Sub    sub                         Summary                 http   openid net specs openid-connect-frontchannel-1 0 html OPLogout         public const string Sid    sid                         Summary                 http   tools ietf org html rfc7519 section-4         public const string Prn    prn                         Summary                 http   tools ietf org html rfc7519 section-4         public const string Nbf    nbf                         Summary                 http   tools ietf org html rfc7519 section-4         public const string Nonce    nonce                         Summary                 http   tools ietf org html rfc7519 section-4         public const string NameId    nameid

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A class that emulates enum behaviour but using string instead of int can be created as follows     public class GrainType       private string  typeKeyWord       private GrainType string typeKeyWord                 typeKeyWord   typeKeyWord             public override string ToString                 return  typeKeyWord             public static GrainType Wheat   new GrainType  GT WHEAT        public static GrainType Corn   new GrainType  GT CORN        public static GrainType Rice   new GrainType  GT RICE        public static GrainType Barley   new GrainType  GT BARLEY         Usage     GrainType myGrain   GrainType Wheat   PrintGrainKeyword myGrain     then     public void PrintGrainKeyword GrainType grain         Console Writeline  My Grain code is     grain ToString          Displays  My Grain code is GT WHEAT

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For people arriving here looking for an answer to a more generic question  you can extend the static class concept if you want your code to look like an enum   The following approach works when you haven t finalised the enum names you want and the enum values are the string representation of the enam name  use nameof   to make your refactoring simpler   public static class Colours       public static string Red   gt  nameof Red       public static string Green   gt  nameof Green       public static string Blue   gt  nameof Blue       This achieves the intention of an enum that has string values  such as the following pseudocode    public enum Colours        Red        Green        Blue

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You can t do this with enums  but you can do it like that   public static class SeparatorChars       public static string Comma             public static string Tab     t        public static string Space

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What I have recently begun doing is using Tuples  public static  string Fox  string Rabbit  string Horse  Animals     Fox    Rabbit    Horse        public static  string Comma  string Tab  string Space  SeparatorChars           t

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Well first you try to assign strings not chars  even if they are just one character  use     instead of      Next thing is  enums only take integral types without char you could use the unicode value  but i would strongly advice you not to do so  If you are certain that these values stay the same  in differnt cultures and languages  i would use a static class with const strings

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I wish there were a more elegant solution  like just allowing string type enum in the language level  but it seems that it is not supported yet  The code below is basically the same idea as other answers  but I think it is shorter and it can be reused  All you have to do is adding a  Description  quot  quot    above each enum entry and add a class that has 10 lines  The class  public static class Extensions       public static string ToStringValue this Enum en                var type   en GetType            var memInfo   type GetMember en ToString             var attributes   memInfo 0  GetCustomAttributes typeof DescriptionAttribute   false           var stringValue     DescriptionAttribute attributes 0   Description          return stringValue           Usage      enum Country                Description  quot Deutschland quot            Germany           Description  quot Nippon quot            Japan           Description  quot Italia quot            Italy             static void Main string   args                Show new    Country Germany  Country Japan  Country Italy             void Show Country   countries                        foreach  var country in countries                                Debug WriteLine country ToStringValue

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Building on some of the answers here I have implemented a reusable base class that mimics the behaviour of an enum but with string as the underlying type  It supports various operations including    getting a list of possible values converting to string comparison with other instances via  Equals      and    conversion to from JSON using a JSON NET JsonConverter   This is the base class in it s entirety   public abstract class StringEnumBase lt T gt    IEquatable lt T gt      where T   StringEnumBase lt T gt        public string Value   get         protected StringEnumBase string value    gt  this Value   value       public override string ToString     gt  this Value       public static List lt T gt  AsList                 return typeof T               GetProperties BindingFlags Public   BindingFlags Static               Where p   gt  p PropertyType    typeof T                Select p   gt   T p GetValue null                ToList               public static T Parse string value                List lt T gt  all   AsList             if   all Any a   gt  a Value    value               throw new InvalidOperationException      value    is not a valid value for the type  typeof T  Name              return all Single a   gt  a Value    value              public bool Equals T other                if  other    null  return false          return this Value    other  Value             public override bool Equals object obj                if  obj    null  return false          if  obj is T other  return this Equals other           return false             public override int GetHashCode     gt  this Value GetHashCode         public static bool operator    StringEnumBase lt T gt  a  StringEnumBase lt T gt  b    gt  a  Equals b     false       public static bool operator    StringEnumBase lt T gt  a  StringEnumBase lt T gt  b    gt    a  Equals b     false        public class JsonConverter lt T gt    Newtonsoft Json JsonConverter         where T   StringEnumBase lt T gt                public override bool CanRead   gt  true           public override bool CanWrite   gt  true           public override bool CanConvert Type objectType    gt  ImplementsGeneric objectType  typeof StringEnumBase lt  gt              private static bool ImplementsGeneric Type type  Type generic                        while  type    null                                if  type IsGenericType  amp  amp  type GetGenericTypeDefinition      generic                      return true                   type   type BaseType                             return false                     public override object ReadJson JsonReader reader  Type objectType  object existingValue  JsonSerializer serializer                        JToken item   JToken Load reader               string value   item Value lt string gt                 return StringEnumBase lt T gt  Parse value                      public override void WriteJson JsonWriter writer  object value  JsonSerializer serializer                        if  value is StringEnumBase lt T gt  v                  JToken FromObject v Value  WriteTo writer                       And this is how you would implement your  string enum     JsonConverter typeof JsonConverter lt Colour gt     public class Colour   StringEnumBase lt Colour gt        private Colour string value    base value           public static Colour Red   gt  new Colour  red        public static Colour Green   gt  new Colour  green        public static Colour Blue   gt  new Colour  blue        Which could be used like this   public class Foo       public Colour colour   get         public Foo Colour colour    gt  this colour   colour       public bool Bar                 if  this colour    Colour Red    this colour    Colour Blue              return true          else             return false            I hope someone finds this useful

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As far as I know  you will not be allowed to assign string values to enum  What you can do is create a class with string constants in it   public static class SeparatorChars       public static String Comma   get   return              public static String Tab   get   return   t            public static String Space   get   return

[c#] How to define an enum with string value?

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