How to combine numbers into a unique sum

Question

I can't remember the name of this, but I remember seeing this once. I need to sum a sequence:

2:hand 
5:leg 
13:head

into one num like 7.

Then when I get 7, I know that it is hand+leg. If I get 20, I know that it is hand+leg+head.

What is the name of this technique?

13 could be a head or 4 hands and a leg. I think you want to be using powers of two. — Josh Gallagher, Nov 04 '12 at 21:20

score 3 · Accepted Answer · answered Nov 04 '12 at 21:21

3

Do you mean a Flags enumeration?

[Flags]
enum Parts
{
    Hand = 1,
    Leg = 2,
    Head = 4,
}

Example:

Parts p = Parts.Hand | Parts.Leg;

bool isHand = (p & Parts.Hand) != 0;

answered Nov 04 '12 at 21:21

dtb

score 2 · Answer 2 · edited May 23 '17 at 12:04

2

You are talking about a bit mask and is typically implemented using an enum decorated with the [FlagsAttribute]. The values would be powers of two.

See the following SO answer for an explanation of using the [FlagsAttribute] in C#.

edited May 23 '17 at 12:04

Community

answered Nov 04 '12 at 21:20

Seth Flowers

score 1 · Answer 3 · answered Nov 04 '12 at 21:21

1

answered Nov 04 '12 at 21:21

usr

3 Answers3