CODEWITHSUNDEEP
c#enumsbit-manipulation
Chuck Savage
Chuck Savage

Reputation: 11945

bitwise join two if's into one

I have this,

public enum Condition : uint // bitwise
{
    None = 0,
    NewLine = 1,
    Space = 2
}

Rule.Condition someCondition = Rule.Condition.Space | Rule.Condition.NewLine;

I'd like to convert this,

if ((Rule.Condition.Space & condition) == Rule.Condition.Space) return true;
if ((Rule.Condition.NewLine & condition) == Rule.Condition.NewLine) return true;

Into something like,

if((someCondition & condition) == someCondition) return true;

But it isn't working. What am I forgetting?

Upvotes: 4

Views: 263

Answers (3)

Rick Sladkey
Rick Sladkey

Reputation: 34240

There is a special convenience method HasFlag in .NET4 expressly for this purpose:

if (condition.HasFlag(someCondition)) return true;

Here's the docs:

Upvotes: 3

sverre
sverre

Reputation: 6919

someCondition has two bits set, one for Rule.Condition.Space and one for Rule.Condition.NewLine. someCondition & condition will have one bit set if condition is Space or NewLine, and be 0 otherwise.

You should test if the bitwise operation returns 0 instead of checking for equality with someCondition

if ((someCondition & condition) != 0) return true

Upvotes: 2

drharris
drharris

Reputation: 11214

Well, if you're just wanting to test for none, then check for > 0. But, if you're looking for a less specific solution, something like this would combine the two and remove the if altogether:

return (int)(someCondition & (Condition.Space | Condition.NewLine)) > 0

Upvotes: 6

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