introduction.md

The C# enum type represents a fixed set of named constants (an enumeration). Normally, one can only refer to exactly one of those named constants. However, sometimes it is useful to refer to more than one constant. To do so, one can annotate the enum with the Flags attribute. A flags enum's constants are interpreted as bitwise flags.

A flags enum can be defined as follows (using binary integer notation):

[Flags]
enum PhoneFeatures
{
    Call = 0b00000001,
    Text = 0b00000010
}

A PhoneFeatures instance which value is 0b00000011 has both its Call and Text flags set.

To work with bits, C# supports the following operators:

• ~: bitwise complement
• <<: left shift
• >>: right shift
• &: logical AND
• |: logical OR
• ^: logial XOR

Here is an example how to use a bitwise operator:

1 << 2
// => 4

By default, the int type is used for enum member values. One can use a different integer type by specifying the type in the enum declaration:

[Flags]
enum PhoneFeatures : byte
{
    Call = 0b00000001,
    Text = 0b00000010
}