Bitwise operations

The operators

Operator	Name
\|	OR
&	AND
^	XOR
<<	Left shift
>>	Right shift
~	Not / One's complement

The OR operator: |

Combines two integers together
For each bit processed if the bit of any of the members is 1, the result will be 1
Used to "activate" bits

The OR operator: |

a:	1	1	0
b:	1	0	1
a\|b	1	1	1

The AND operator: &

Filter active bits
For each bit processed if the bits of both members is 1, the result will be 1
Used for masks

The AND operator: &

a:	1	1	0
b:	1	0	1
a&b	1	0	0

The XOR operator: ^

Toggle bits
For each bit processed if the bits of both members is the same, the result will be 0, otherwise 1

The XOR operator: ^

a:	1	1	0
b:	1	0	1
a^b	0	1	1

The left shift: <<

Shifts all bits to the left
Discards the overflowing bits
Sets to 0 the right most bits
AKA: Multiplies by 2

The left shift: <<

a:	0	0	1	1	0	1	= 13
a << 1	0	1	1	0	1	0	= 26
a << 2	1	1	0	1	0	0	= 52

The right shift: >>

Shifts all bits to the right
Discards the underflowing bits
Sets to 0 the left most bits
AKA: Divides by 2

The right shift: >>

a:	1	1	0	1	0	0	= 52
a >> 1	0	1	1	0	1	0	= 26
a >> 2	0	0	1	1	0	1	= 13

And my personal favourite....

The not: ~

Applied to a single value
Toggles all the member's bits
Used to create mask

Or complement to one

The not: ~

With signed integers:

~a = -1 * a - 1

~-1 = 0

Or complement to one

if (array.indexOf(val) == -1) // if NOT found

if (!~array.indexOf(val)) // if NOT found

Real life usages

Group errors in a single value

Create an error reporting

Real life usages

Networking

Encryption

Real life usages

Color storage

RGB color:

Red: 0 to 255, 1byte
Green: 0 to 255, 1byte
Blue: 0 to 255, 1byte
Alpha: 0 to 255, 1byte

Real life usages

Color storage

Can be stored in a long (4 bytes)

#B2A3C5CC

R: B2 (178), G: A3 (163), B: C5 (197), A: CC (204)

10110010

10100011

11000101

11001100

which is -1297889844

Real life usages

Color storage

Components retrieval

Red value = (color >> 24) & 255

Green value = (color >> 16) & 255

Blue value = (color >> 8) & 255

Alpha value = color & 255

Real life usages

Flags storage

Collection of boolean values

Can be replaced with a single int to store up to 32 flags

Each boolean take 1 byte in memory

Operations to know

Activate a bit

Deactivate a bit

Get a bit value

Activate a bit

value | (1 << bitIndex)

Deactivate a bit

value & ~(1 << bitIndex)

Get a bit value

value & (1 << bitIndex)