How to set enum to null

Question

I have an enum  string name   public enum Color     Red    Green    Yellow     How to set it to NULL on load   name       Color color   null    error   Edited   My bad  I didn t explain it properly  But all the answers related to nullable is perfect  My situation is What if  I have get set for the enum in a class with other elements like name  etc  On page load I initiallize the class and try to default the values to null  Here is the scenario  Code is in C     namespace Testing       public enum ValidColors               Red          Green          Yellow            public class EnumTest               private string name          private ValidColors myColor           public string Name                       get   return name                set   name   value                       public ValidColors MyColor                       get   return myColor                set   myColor   value                          public partial class  Default   System Web UI Page                      protected void Page Load object sender  EventArgs e                        EnumTest oEnumTest   new EnumTest                oEnumTest Name                   oEnumTest MyColor   null                             Then using the suggestions below I changed the above code to make it work with get and set methods  I just need to add     in EnumTest class during declaration of private enum variable and in get set method   public class EnumTest       private string name      private ValidColors  myColor    added     here in declaration and in get set method      public string Name               get   return name            set   name   value               public ValidColors  MyColor               get   return myColor            set   myColor   value               Thanks all for the lovely suggestions

User · Accepted Answer

You can either use the     operator for a nullable type   public Color  myColor   null    Or use the standard practice for enums that cannot be null by having the FIRST value in the enum  aka 0  be the default value  For example in a case of color None   public Color myColor   Color None

User · Answer

would it not be better to explicitly assign value 0 to None   constant   Why    Because default enum value is equal to 0  if You would call default Color  it would print None   Because it is at first position  assigning literal value 0 to any other constant would change that behaviour  also changing order of occurrence would change output of default Color   https   stackoverflow com a 4967673 8611327

User · Answer

I m assuming c   here  If you re using c   the answer is probably the same  but the syntax will be a bit different   The enum is a set of int values  It s not an object  so you shouldn t be setting it to null  Setting something to null means you are pointing a pointer to an object to address zero  You can t really do that with an int  What you want to do with an int is to set it to a value you wouldn t normally have it at so that you can tel if it s a good value or not  So  set your colour to -1  Color color   -1    Or  you can start your enum at 1 and set it to zero  If you set the colour to zero as it is right now  you will be setting it to  red  because red is zero in your enum   So   enum Color   red  1 blue  green     red is 1  blue is 2  green is 3 Color mycolour   0

User · Answer

If this is C   it won t work  enums are value types  and can t be null   The normal options are to add a None member   public enum Color     None    Red    Green    Yellow    Color color   Color None       or to use Nullable   Color  color   null

User · Answer

Make your variable nullable   Like   Color  color   null    or  Nullable lt Color gt  color   null

User · Answer

Color  color   null    or you can use   Color  color   new Color       example where assigning null wont work  color   x    5   Color Red   x    9   Color Black   null      so you can use     color   x    5   Color Red   x    9   Color Black   new Color

User · Answer

An enum is a  value  type in C   means the the enum is stored as whatever value it is  not as a reference to a place in memory where the value itself is stored    You can t set value types to null  since null is used for reference types only    That being said you can use the built in Nullable lt T gt  class which wraps value types such that you can set them to null  check if it HasValue and get its actual Value   Those are both methods on the Nullable lt T gt  objects   name       Nullable lt Color gt  color   null    This will work    There is also a shortcut you can use   Color  color   null    That is the same as Nullable lt Color gt

[c#] How to set enum to null

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