What does the [Flags] Enum Attribute mean in C#?

The [Flags] attribute in C# is used to indicate that an enum is intended to be used as a set of bit flags, where each enum value represents a single bit position. This allows you to combine multiple enum values using bitwise operations.

When you apply the [Flags] attribute to an enum, it doesn't change the behavior of the enum itself but provides a hint to developers that the enum is meant to be used for bitwise operations.

Here's an example to illustrate the use of the [Flags] attribute:

csharp

[Flags]
enum Permissions
{
    None = 0,
    Read = 1,
    Write = 2,
    Execute = 4,
    Delete = 8
}

class Program
{
    static void Main()
    {
        Permissions userPermissions = Permissions.Read | Permissions.Write;

        Console.WriteLine($"User permissions: {userPermissions}");
    }
}

In this example, the Permissions enum is decorated with the [Flags] attribute. The enum values are assigned powers of 2 to allow bitwise combinations.

The Main method demonstrates how to combine enum values using bitwise OR (|) to represent multiple permissions. The result will be a value that can be used to check for specific permissions using bitwise AND (&).

When you run this code, you'll see that the combined enum values are displayed as a single value:

mathematica

User permissions: Read, Write

Keep in mind that while the [Flags] attribute provides a helpful hint to developers, it doesn't enforce bitwise operations or validity of flag combinations. It's up to you to ensure that you're using bitwise operations correctly and that the enum values make sense when combined.