Enums
attributes? access-modifier? new? enum enum-name [ : integer-type ]? { [attributes? enum-member-name [ = value ]? ]* }
Enums specify a group of named numeric constants:
public enum Direction {North, East, West, South}
Unlike in C, enum members must be used with the enum type name. This resolves naming conflicts and makes code clearer:
Direction walls = Direction.East;
By default, enums are assigned integer constants 0, 1, 2, etc. You may optionally specify an alternative numeric type to base your enum on, and explicitly specify values for each enum member:
[Flags] public enum Direction : byte { North=1, East=2, West=4, South=8 } Direction walls = Direction.North | Direction.West; if((walls & Direction.North) != 0) System.Console.WriteLine("Can't go north!");
The [Flags]
attribute is optional, and informs the
runtime that the values in the enum can be bit-combined, and should be decoded
accordingly in the debugger or when outputting text to the console. For example:
Console.WriteLine(walls.Format()); // Displays "North|West" Console.WriteLine(walls); // Calls walls.ToString, displays "5"
The System.Enum
type also provides many useful static
methods for enums that allow one to determine the underlying type of an enum,
to check if a specific value is supported, to initialize an enum from a string
constant, to retrieve a list of the valid values, and other common operations
such as conversions. Here is an example of the usage:
using System; public enum Toggle : byte { Off=0, On=1 } class ...
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