O'Reilly logo

C# Essentials by Peter Drayton, Ben Albahari, Brad Merrill

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

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 can 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. It 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 you 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:

using System; public enum Toggle : byte { Off=0, On=1 } class TestEnum ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required