algorithmbitmaskbitflags

Is there a name for the technique of using base-2 numbers to encode a list of unique options?

I am writing a couple of functions that encode and decode a list of options into a Long so they can easily be passed around the application, you know this kind of thing:

1 - Apple
2 - Orange
4 - Banana
8 - Plum
etc.

In this case the number 11 would represent Apple, Orange & Plum.

I've got it working but I see this used all the time so assume there is a common name for the technique, and no doubt all sorts of best practice and clever algorithms that are at the moment just out of my reach.

Solution

  • Bit Flags. It's a technique used as part of Bitmasking.

    0001 - Apple
    0010 - Oranage
    0100 - Banana
    1000 - Plum

    Each 1 is the flagged bit.

    Now you can easily perform bitwise operations using those number:

    if((11 & Apple) == Apple) // The Apple Flag is set
{
    // Do Something
}