bitwise.md

from Binary and Bitwise Operations in Ruby by CooperPress http://goo.gl/4uQY7f

Bitwise

Representation

How to represent base 2, 8, 10, 16 in Integer?

0b1010
012
10
0xA

How to represent base 2, 8, 10, 16 in String?

"1010"
"12"
"10"
"A"

Exchange

How to change representation from Integer to String?

0b1010.to_s(2) # => "1010"
012.to_s(8)    # => "12"
10.to_s        # => "10"
0xA.to_s(16)   # => "A"

How to change representation from String to Integer?

"1010".to_i(2) # => 10
"12".to_i(8)   # => 10
"10".to_i      # => 10
"A".to_i(16)   # => 10

Operation

• and, &
• or, |
• xor, ^
• not, ~
• shift, <<, >>

(0b101 & 0b110).to_s(2) # => "100"
(0b101 | 0b110).to_s(2) # => "111"
(0b101 ^ 0b110).to_s(2) # => "11"
(~0b101).to_s(2)        # => "-110"
(0b101 << 1).to_s(2)    # => "1010"
(0b1010 >> 1).to_s(2)   # => "101"

Usage

Use >> and << to multiply or divide by 2.

24 << 1                 # => 48
24 << 2                 # => 96
37 >> 1                 # => 18

Use & as a mask.

"01101001".to_i(2)      # => 105

0b11110000 & 0b01101001 # => 96
96 >> 4                 # => 6

0b00001111 & 0b01101001 # => 9

Use &, | and ^ to check, set, unset a state.

PRIVATE   = 1
PUBLISHED = 2
DELETED   = 4

flags = 0

# use | to set a state
flags |= PRIVATE        # => 1
flags |= PUBLISHED      # => 3

# use & to check a state
flags & PRIVATE         # => 1
flags & PUBLISHED       # => 2
flags & DELETED         # => 0

# use ^ to unset a state
flags ^= PRIVATE        # => 2
flags &  PRIVATE        # => 0