Bitwise Boolean Expressions

The bitwise operators work bit by bit on the operands. The operands must be of integral type (one of the types used for integers). The six bitwise operators are & (AND), | (OR), ^ (exclusive OR, commonly called XOR), ~ (NOT, which changes 1 to 0 and 0 to 1), << (shift left), and >> (shift right). The negation operator is a unary operator which preceeds the operand. The others are binary operators which lie between the two operands. The precedence of these operators is lower than that of the relational and equivalence operators; it is often required to parenthesize expressions involving bitwise operators.

For this section, recall that a number starting with 0x is hexadecimal, or hex for short. Unlike the normal decimal system using powers of 10 and digits 0123456789, hex uses powers of 16 and digits 0123456789abcdef. It is commonly used in C programs because a programmer can quickly convert it to or from binary (powers of 2 and digits 01). C does not directly support binary notation, which would be really verbose anyway.

a & b

bitwise boolean and of a and b

0xc & 0xa produces the value 0x8 (in binary, 1100 & 1010 produces 1000)

a | b

bitwise boolean or of a and b

0xc | 0xa produces the value 0xe (in binary, 1100 | 1010 produces 1110)

a ^ b

bitwise xor of a and b

0xc ^ 0xa produces the value 0x6 (in binary, 1100 ^ 1010 produces 0110)

~a

bitwise complement of a.

~0xc produces the value -1-0xc (in binary, ~1100 produces ...11110011 where "..." may be many more 1 bits)

a << b

shift a left by b (multiply a by 2^b)

0xc << 1 produces the value 0x18 (in binary, 1100 << 1 produces the value 11000)

a >> b

shift a right by b (divide a by 2^b)

0xc >> 1 produces the value 0x6 (in binary, 1100 >> 1 produces the value 110)

 

 

 

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