C int to enum conversion

Question

Possible Duplicate    Cast int to enum in C        If I have the following code   enum foo   int       option1   1      option2             private foo convertIntToFoo int value           Convert int to respective Foo value or throw exception     What would the conversion code look like

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Casting should be enough  If you re using C  3 0 you can make a handy extension method to parse enum values   public static TEnum ToEnum lt TInput  TEnum gt  this TInput value        Type type   typeof TEnum        if  value    default TInput                 throw new ArgumentException  Value is null or empty     value               if   type IsEnum                throw new ArgumentException  Enum expected     TEnum               return  TEnum Enum Parse type  value ToString    true

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if  Enum IsDefined typeof foo   value        return  Foo Enum Parse typeof foo   value       Hope this helps  Edit This answer got down voted as value in my example is a string  where as the question asked for an int  My applogies  the following should be a bit clearer  -   Type fooType   typeof foo    if  Enum IsDefined fooType   value ToString          return  Foo Enum Parse fooType   value ToString

User · Answer

Casting should be enough  If you re using C  3 0 you can make a handy extension method to parse enum values   public static TEnum ToEnum lt TInput  TEnum gt  this TInput value        Type type   typeof TEnum        if  value    default TInput                 throw new ArgumentException  Value is null or empty     value               if   type IsEnum                throw new ArgumentException  Enum expected     TEnum               return  TEnum Enum Parse type  value ToString    true

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You don t need the inheritance  You can do    Foo 1    it will work

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It s fine just to cast your int to Foo   int i   1  Foo f    Foo i    If you try to cast a value that s not defined it will still work  The only harm that may come from this is in how you use the value later on   If you really want to make sure your value is defined in the enum  you can use Enum IsDefined   int i   1  if  Enum IsDefined typeof Foo   i         Foo f    Foo i    else         Throw exception  etc      However  using IsDefined costs more than just casting  Which you use depends on your implemenation  You might consider restricting user input  or handling a default case when you use the enum   Also note that you don t have to specify that your enum inherits from int  this is the default behavior

User · Answer

It s fine just to cast your int to Foo   int i   1  Foo f    Foo i    If you try to cast a value that s not defined it will still work  The only harm that may come from this is in how you use the value later on   If you really want to make sure your value is defined in the enum  you can use Enum IsDefined   int i   1  if  Enum IsDefined typeof Foo   i         Foo f    Foo i    else         Throw exception  etc      However  using IsDefined costs more than just casting  Which you use depends on your implemenation  You might consider restricting user input  or handling a default case when you use the enum   Also note that you don t have to specify that your enum inherits from int  this is the default behavior

User · Answer

You don t need the inheritance  You can do    Foo 1    it will work

User · Answer

You don t need the inheritance  You can do    Foo 1    it will work

User · Answer

if  Enum IsDefined typeof foo   value        return  Foo Enum Parse typeof foo   value       Hope this helps  Edit This answer got down voted as value in my example is a string  where as the question asked for an int  My applogies  the following should be a bit clearer  -   Type fooType   typeof foo    if  Enum IsDefined fooType   value ToString          return  Foo Enum Parse fooType   value ToString

User · Answer

I m pretty sure you can do explicit casting here   foo f    foo value    So long as you say the enum inherits    from int  which you have   enum foo   int   EDIT Yes it turns out that by default  an enums underlying type is int  You can however use any integral type except char   You can also cast from a value that s not in the enum  producing an invalid enum  I suspect this works by just changing the type of the reference and not actually changing the value in memory   enum  C  Reference  Enumeration Types  C  Programming Guide

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I m pretty sure you can do explicit casting here   foo f    foo value    So long as you say the enum inherits    from int  which you have   enum foo   int   EDIT Yes it turns out that by default  an enums underlying type is int  You can however use any integral type except char   You can also cast from a value that s not in the enum  producing an invalid enum  I suspect this works by just changing the type of the reference and not actually changing the value in memory   enum  C  Reference  Enumeration Types  C  Programming Guide

User · Answer

I m pretty sure you can do explicit casting here   foo f    foo value    So long as you say the enum inherits    from int  which you have   enum foo   int   EDIT Yes it turns out that by default  an enums underlying type is int  You can however use any integral type except char   You can also cast from a value that s not in the enum  producing an invalid enum  I suspect this works by just changing the type of the reference and not actually changing the value in memory   enum  C  Reference  Enumeration Types  C  Programming Guide

User · Answer

I m pretty sure you can do explicit casting here   foo f    foo value    So long as you say the enum inherits    from int  which you have   enum foo   int   EDIT Yes it turns out that by default  an enums underlying type is int  You can however use any integral type except char   You can also cast from a value that s not in the enum  producing an invalid enum  I suspect this works by just changing the type of the reference and not actually changing the value in memory   enum  C  Reference  Enumeration Types  C  Programming Guide

User · Answer

It s fine just to cast your int to Foo   int i   1  Foo f    Foo i    If you try to cast a value that s not defined it will still work  The only harm that may come from this is in how you use the value later on   If you really want to make sure your value is defined in the enum  you can use Enum IsDefined   int i   1  if  Enum IsDefined typeof Foo   i         Foo f    Foo i    else         Throw exception  etc      However  using IsDefined costs more than just casting  Which you use depends on your implemenation  You might consider restricting user input  or handling a default case when you use the enum   Also note that you don t have to specify that your enum inherits from int  this is the default behavior

User · Answer

It s fine just to cast your int to Foo   int i   1  Foo f    Foo i    If you try to cast a value that s not defined it will still work  The only harm that may come from this is in how you use the value later on   If you really want to make sure your value is defined in the enum  you can use Enum IsDefined   int i   1  if  Enum IsDefined typeof Foo   i         Foo f    Foo i    else         Throw exception  etc      However  using IsDefined costs more than just casting  Which you use depends on your implemenation  You might consider restricting user input  or handling a default case when you use the enum   Also note that you don t have to specify that your enum inherits from int  this is the default behavior

User · Answer

Casting should be enough  If you re using C  3 0 you can make a handy extension method to parse enum values   public static TEnum ToEnum lt TInput  TEnum gt  this TInput value        Type type   typeof TEnum        if  value    default TInput                 throw new ArgumentException  Value is null or empty     value               if   type IsEnum                throw new ArgumentException  Enum expected     TEnum               return  TEnum Enum Parse type  value ToString    true

User · Answer

Casting should be enough  If you re using C  3 0 you can make a handy extension method to parse enum values   public static TEnum ToEnum lt TInput  TEnum gt  this TInput value        Type type   typeof TEnum        if  value    default TInput                 throw new ArgumentException  Value is null or empty     value               if   type IsEnum                throw new ArgumentException  Enum expected     TEnum               return  TEnum Enum Parse type  value ToString    true

User · Answer

if  Enum IsDefined typeof foo   value        return  Foo Enum Parse typeof foo   value       Hope this helps  Edit This answer got down voted as value in my example is a string  where as the question asked for an int  My applogies  the following should be a bit clearer  -   Type fooType   typeof foo    if  Enum IsDefined fooType   value ToString          return  Foo Enum Parse fooType   value ToString

User · Answer

You don t need the inheritance  You can do    Foo 1    it will work

User · Answer

if  Enum IsDefined typeof foo   value        return  Foo Enum Parse typeof foo   value       Hope this helps  Edit This answer got down voted as value in my example is a string  where as the question asked for an int  My applogies  the following should be a bit clearer  -   Type fooType   typeof foo    if  Enum IsDefined fooType   value ToString          return  Foo Enum Parse fooType   value ToString

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