CODEWITHSUNDEEP
c#bitwise-operatorsenum-flags
Tony_KiloPapaMikeGolf
Tony_KiloPapaMikeGolf

Reputation: 889

Bitwise operations on Enum Flag

Assume you have the following Enumeration, which contains flags.

[Flags]
public enum MyFlag
{
    None = 0,
    Foo = 1 << 0,
    Bar = 1 << 1,
    Baz = 1 << 2,
    Quuz = 1 << 3
}

And you instantiate a new and old :

var newF = MyFlag.Foo | MyFlaq.Quuz; // 1001
var oldF = MyFlag.Foo | MyFlag.Baz;  // 0101

My first question: How to perform a bitwise operation on new and old, getting the XOR flag ?

var xor = ?????  // -> should be    1100

Then an additional question: How to use that XOR flags, to calculate added and removed flags?

MyFlag added = ????? // Do something with new and xor -> should result in : 1000
MyFlag removed = ????? // Do same thing with old and xor -> should result in: 0100

Doing this manually on a piece of paper is super easy.

Bitwise operation on paper.

There should be some kind of bitwise operation available for this right? Please show me the answer and I will add it to my skillset! :-)

The answers are:

var xor = newF ^ oldF;
var added = newF & xor;
var removed = oldF & xor;

Upvotes: 0

Views: 2998

Answers (1)

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186688

Try ^; please, notice that new is a keyword in C# and that's why should be put as @new when it's used as a name:

  var @new = MyFlag.Foo | MyFlag.Quuz; // 1001
  var old = MyFlag.Foo | MyFlag.Baz;   // 0101

  var xor = @new ^ old; // <- xor

Test

  // 1100
  Console.Write(Convert.ToString((int)xor, 2));

Finally, it seems that you are looking for bitwise & to obtain added and removed values:

  MyFlag added = xor & @new;  // 1000
  MyFlag removed = xor & old; // 0100

Upvotes: 3

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