Bitwise Manipulation

Bitwise Manipulation:

Bit manipulation is the act of algorithmically manipulating bits or other pieces of data shorter than a byte. C language is very efficient in manipulating bits. Here are following operators to perform bit manipulation: Bitwise Operators: C provides six operators for bit manipulation. Symbol Operator & bitwise AND | bitwise inclusive OR ^ bitwise exclusive OR <<  left shift >>  right shift ~ bitwise NOT (one's complement) (unary) Bitwise operator works on bits and perform bit by bit operation. Assume if B = 60; and B = 13; Now in binary format they will be as follows: A = 0011 1100 B = 0000 1101 ----------------- A&B = 0000 1100 A|B = 0011 1101 A^B = 0011 0001 ~A  = 1100 0011 Examples Bitwise operators supported by C language with Description and Example Operator Description Example & Binary AND Operator copies a bit to the result if it exists in both operands. (A & B) will give 12 which is 0000 1100 | Binary OR Operator copies a bit if it exists in eather operand. (A | B) will give 61 which is 0011 1101 ^ Binary XOR Operator copies the bit if it is set in one operand but not both. (A ^ B) will give 49 which is 0011 0001 ~ Binary Ones Complement Operator is unary and has the efect of 'flipping' bits. (~A ) will give -60 which is 1100 0011 <<  Binary Left Shift Operator. The left operands value is moved left by the number of bits specified by the right operand. A << 2 will give 240 which is 1111 0000 >>  Binary Right Shift Operator. The left operands value is moved right by the number of bits specified by the right operand. A >> 2 will give 15 which is 0000 1111 The shift operators perform appropriate shift by operator on the right to the operator on the left. The right operator must be positive. The vacated bits are filled with zero. For example: x << 2 shifts the bits in x by 2 places to the left. if x = 00000010 (binary) or 2 (decimal) then: x >>= 2 => x = 00000000 or just 0 (decimal) Also: if x = 00000010 (binary) or 2 (decimal) then x <<= 2 => x = 00001000 or 8 (decimal) Uses of Bitwise Operators Therefore a shift left is equivalent to a multiplication by 2. Similarly a shift right is equal to division by 2. Shifting is much faster than actual multiplication (*) or division (/) by 2. So if you want fast multiplications or division by 2 use shifts.

Bitwise AND is often used to test whether a particular bit is 1 or 0.

Bitwise OR is often used to set a particular bit to 1.

Bitwise COMPLIMENT is often combined with AND  to turn off a particular bit.

We can also use bits to represent elements of a (small) set. If a bit is 1, then element i is in the set, otherwise it's not.

We can use bitwise AND to implement set intersection, bitwise OR to implement set union.