Mod of power 2 on bitwise operators?
- How does mod of power of 2 work on only lower order bits of a binary number (
- What is this number mod 2 to power 0, 2 to power 4?
- What does power of 2 have to do with the modulo operator? Does it hold a special property?
- Can someone give me an example?
The instructor says "When you take something mod to power of 2 you just take its lower order bits". I was too afraid to ask what he meant =)
He meant that taking
number mod 2^n is equivalent to stripping off all but the
n lowest-order (right-most) bits of
For example, if n == 2,
number number mod 4 00000001 00000001 00000010 00000010 00000011 00000011 00000100 00000000 00000101 00000001 00000110 00000010 00000111 00000011 00001000 00000000 00001001 00000001 etc.
So in other words,
number mod 4 is the same as
number & 00000011 (where
& means bitwise-and)
Note that this works exactly the same in base-10:
number mod 10 gives you the last digit of the number in base-10,
number mod 100 gives you the last two digits, etc.