Bit manipulation (since C++20)

Provides several function templates to access, manipulate, and process individual bits and bit sequences.

Defined in header <bit>
Defined in namespace std
bit_cast (C++20)	reinterpret the object representation of one type as that of another (function template)
byteswap (C++23)	reverses the bytes in the given integer value (function template)
Integral powers of 2
has_single_bit (C++20)	checks if a number is an integral power of 2 (function template)
bit_ceil (C++20)	finds the smallest integral power of 2 not less than the given value (function template)
bit_floor (C++20)	finds the largest integral power of 2 not greater than the given value (function template)
bit_width (C++20)	finds the smallest number of bits needed to represent the given value (function template)

Shifting (since C++29)
shl (C++29)	shifts to the left without the possibility of undefined behavior (function template)
shr (C++29)	shifts to the right without the possibility of undefined behavior (function template)
Rotating
rotl (C++20)	computes the result of bitwise left-rotation (function template)
rotr (C++20)	computes the result of bitwise right-rotation (function template)
Counting
countl_zero (C++20)	counts the number of consecutive 0 bits, starting from the most significant bit (function template)
countl_one (C++20)	counts the number of consecutive 1 bits, starting from the most significant bit (function template)
countr_zero (C++20)	counts the number of consecutive 0 bits, starting from the least significant bit (function template)
countr_one (C++20)	counts the number of consecutive 1 bits, starting from the least significant bit (function template)
popcount (C++20)	counts the number of 1 bits in an unsigned integer (function template)

Permutation (since C++29)
bit_reverse (C++29)	reverses the bits in an integer (function template)
bit_repeat (C++29)	repeats/broadcasts a bit pattern of specified length (function template)
bit_compress (C++29)	compresses bits of an operand using a mask (PEXT) (function template)
bit_expand (C++29)	expands bits from an operand using a mask (PDEP) (function template)
Endian
endian (C++20)	indicates the endianness of scalar types (enum)

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_bit_cast	201806L	(C++20)	std::bit_cast
__cpp_lib_bitops	201907L	(C++20)	Bit operations
	202606L	(C++29)	Better shifting
	202607L	(C++29)	Bit permutation
__cpp_lib_byteswap	202110L	(C++23)	std::byteswap
__cpp_lib_int_pow2	202002L	(C++20)	Integral power-of-2 operations
__cpp_lib_stdbit_h	202603L	(C++26)	Compatibility header <stdbit.h> for C bitwise operations

See also

C documentation for Bit manipulation