Bitmanipulation

Bit manipulation refers to the direct manipulation of individual bits within binary data. It is a low-level technique used to implement flags, compact data representations, and performance-critical algorithms in systems programming, embedded contexts, and performance-sensitive software. Most programming languages expose a set of bitwise operations that operate on integers and, in some cases, on other integral types.

The core operations include AND, OR, XOR, and NOT, which combine or invert bits. Shifts move bits left or right: left shift (<<) and right shift (>>). In some languages there is a separate unsigned right shift (>>>). Masks—values whose bits indicate which positions to target—are central to most bit-manipulation tasks. Typical patterns include setting, clearing, toggling, or testing a specific bit. For example, to set bit n in x, one uses x = x | (1 << n); to clear it, x = x & ~(1 << n); to toggle, x = x ^ (1 << n); and to test, (x & (1 << n)) != 0.

Rotations are related operations that move bits around in a circular fashion, producing rotate-left and rotate-right effects. Although not always built-in, they are constructed from shifts and masks in many languages. Bit manipulation also encompasses techniques such as masking to pack or unpack fields, bit-field access, and advanced twiddling hacks (for example, clearing the lowest set bit with x = x & (x - 1)) and population counting.

Common applications include managing flags and permissions efficiently, packing data into compact formats for storage or transmission, implementing fast parsers, error-detection codes, cryptographic primitives, and graphics or multimedia processing. While powerful, bit manipulation can reduce readability and portability if not well-documented, and some languages impose rules about shifts and signedness that affect correctness.