bits

Bits

Basic Operators

AND:

x	y	x & y
0	0	0
0	1	0
1	0	0
1	1	1

OR:

x	y	x | y
0	0	0
0	1	1
1	0	1
1	1	1

XOR:

x	y	x ^ y
0	0	0
0	1	1
1	0	1
1	1	0

Shifts

Disclaimer: We are taking byte (8 bits) as our datatype to explain the concepts instead of the usual integer.

1. Left Shift (<<):

1 << 3 = 8

00000001 << 3 = 00001000

2. Right Shift:

Two types:

a. Signed Right Shift (>>):

64 >> 2 = 16

001000000 >> 2 = 00010000

-64 >> 2 = -16

111000000 >> 2 = 11110000

b. Unsigned Right Shift (>>>):

64 >>> 2 = 16

001000000 >>> 2 = 00010000

-64 >>> 2 = 56

111000000 >>> 2 = 00111000

Helpful Masks

1. Set the 4th bit from right:

byte mask = 1 << 3;

Explanation,

00000001 << 3 = 00001000

2. Set the first 3 bits from right:

byte mask = (1 << 3) - 1;

Explanation,

00000001 << 3 = 00001000

00001000 - 00000001 = 00000111

3. Mask with alternating 1010...10

byte mask = 0x55;

4. Mask with alternating 0101...01

byte mask = 0xaa;

5. Unset the 4th bit

byte mask = 1 << 3;

byte num = num & ~mask;

Explanation,

00000001 << 3 = 00001000

~(00001000) = 11110111