C Pocket Reference

Bitwise Operators

There are six bitwise operators, described in Table 1-13. All of them require integer operands.

Table 1-13. The bitwise operators

Operator	Meaning	Example	Result (for each bit position)
&	bitwise AND	x & y	1, if 1 in both x and y
|	bitwise OR	x | y	1, if 1 in either x or y, or both
^	bitwise exclusive OR	x ^ y	1, if 1 in either x or y, but not both
~	bitwise NOT	~x	1, if 0 in x
<<	shift left	x << y	Each bit in x is shifted y positions to the left
>>	shift right	x >> y	Each bit in x is shifted y positions to the right

The logical bitwise operators, & (AND), | (OR), ^ (exclusive OR), and ~ (NOT) interpret their operands bit by bit: a bit that is set, i. e., 1, is considered “true”; a cleared bit, or 0, is “false”. Thus, in the result of z = x & y, each bit is set if and only if the corresponding bit is set in both x and y. The usual arithmetic conversions are performed on the operands.

The shift operators << and >> transpose the bit pattern of the left operand by the number of bit positions indicated by the right operand. Integer promotions are performed beforehand on both operands. The result has the type of the left operand after integer promotion. Some examples are:

int  x = 0xF, result; 
result = x << 4; // yields 0xF0
result = x >> 2; // yields  0x3

The bit positions vacated at the right by the left shift << are always filled with 0 bits. Bit values shifted out to the left are lost.

The bit positions vacated at the ...