Bitwise Operators

Bitwise Operators

Bitwise operators are operators that enable us to manipulate individual bits of data or information. Most of bitwise operators are binary, meaning they need a left operand and a right operand. The only unary operator is ~.

AND (&)

• Performs logical conjunction
• Only when both left and right operands are 1, the result of the bitwise AND is 1.
• If left or right operand is 0, the result of the bitwise AND is 0.
• If both left and right operands are 0, the result of the bitwise AND is 0.

OR (|)

• Performs logical disjunction
• If at least one of left or right operands are 1, the result of the bitwise OR is 0.

XOR (^)

• Performs exclusive disjunction on the bit pairs
• a XOR b is (a and not b) or (not a and b)
• It evaluates two mutually exclusive conditions
• ex: a person can be either a minor or an adult, but not both at the same time
• Produces 1 only when every bit pair contains opposing bit values
• (a ^ b) = (a + b) mod 2

NOT (~)

• Expects one argument (unary bitwise operator)
• Performs logical negation on a given number by flipping all of its bits
• ~(1000) is 0111

Left Shift («)

• Moves the bits of its first operand to the left by the number of places specified in its second operand
• Fills the gap that arises on the right edge of the new bit pattern.
• 1101 << 2 is 110100
• Shifting a single bit to the left by one place doubles its value. It corresponds to multiplying the number by a power of two.
• a << n is a x 2^n
• Left shift is used to be a popular optimization technique because bit shifting is a single instruction and cheaper than exponent or product.
• If working with a single byte, shifting to the left discards all the bits that go beyond its left boundary.
  • 10011 << 2 is 01100

Right Shift (»)

• Pushes bits to the right by the specified number of places and the rightmost bits always get dropped.
• By shifting a bit to the right by one position, the value gets halved.
• 1001101 >> 2 is 0010011
• a >> n is floor(a / (2^n))

Reference

Bitwise Operators in Python