Ivor Horton's Beginning Visual C++ 2012

THE BITWISE OPERATORS

The bitwise operators treat their operands as a series of individual bits rather than a numerical value. They work only with integer variables or integer constants as operands, so only data types short, int, long, long long, signed char, and char, as well as the unsigned variants of these, can be used. The bitwise operators are useful in programming hardware devices, where the status of a device is often represented as a series of individual flags (that is, each bit of a byte may signify the status of a different aspect of the device), or for any situation where you might want to pack a set of on-off flags into a single variable. You will see them in action when you look at input/output in detail, where single bits are used to control various options in the way data is handled.

There are six bitwise operators:

& bitwise AND	| bitwise OR	^ bitwise exclusive OR
~ bitwise NOT	>> shift right	<< shift left

The following sections explain how each of them works.

The Bitwise AND

The bitwise AND, &, is a binary operator that combines corresponding bits in its operands in a particular way. If both corresponding bits are 1, the result is a 1 bit, and if either or both bits are 0, the result is a 0 bit.

The effect of a particular binary operator is often shown using what is called a truth table. This shows, for various possible combinations of operands, what the result is. The truth table for & is as follows:

Bitwise AND	0	1
0	0	0
1	0	1

For each row ...