How much memory does an enum take? [duplicate]

Question

I need to decide if I will use enums in a big array I need in my project. To do that I have to know what is size of an enum variable.

enum Player 
{ 
     First, 
     Second, 
     Third, 
     Fourth 
};

private Player _owner;

How much memory will _owner take?

I haven't found proper information about this in C#, that's why this C++ and Java topic does not apply: How much memory do Enums take?

Answer 1

Enum values are converted to values of the underlying type at compile time. Therefore, a variable of an enumeration type itself based on int type (which is the default) doesn't use any more memory than any other int variable in your code.

An Enum underlying structure can be any of the following:

• byte
• sbyte
• short
• ushort
• int
• uint
• long
• ulong

Since your Player enumeration type does not specify the underlying time, the compiler will see it as an int-based Enum. If memory is a concern, you may want to consider declaring it as derived from byte instead:

enum Player : byte
{ 
    First, 
    Second, 
    Third, 
    Fourth 
};

Be careful though: a newly declared Enum variable will have the same value as it's underlying type's default value, which will always be zero. In an enum with unspecified literal values, the first item in the list is assumed as the default value. In your case, that would be First:

private Player _owner; // this value will initially equals Player.First

You may want to insert an additional Player literal labelled None, Empty or Undefined to represent a Player variable default value:

enum Player : byte
{ 
    Undefined = 0;
    First, 
    Second, 
    Third, 
    Fourth 
};

private Player _owner; // this value will initially equals Player.Undefined

Of course, if you are okay having First as the default value, you may leave it as is. Be aware though that not having a dedicated default Enum value is often considered a bad coding practice.

As an alternative, since any Enum are structure-based, you may also declare your _owner variable as Player? so that it will instead be null by default:

private Player? _owner; // this value will initially equals null

To sum it up, simply remember that Enum literals simply acts as constants for their underlying type. Their purpose is to make code easier to read and to enforce a limited set of possible values at compile time.

For more information, look at the documentation.