std::rotl
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rotl
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Defined in header
<bit>
template< class T >
constexpr T rotl( T x, int s ) noexcept;
(since C++20)
constexpr T rotl( T x, int s ) noexcept;
Computes the result of bitwise left-rotating the value of x by s positions. This operation is also known as a left circular shift.
Formally, let N be std::numeric_limits <T>::digits and r be s % N.
- If r is 0, returns x;
- if r is positive, returns (x << r) | (x >> (N - r));
- if r is negative, returns std::rotr (x, -r).
This overload participates in overload resolution only if T is an unsigned integer type (that is, unsigned char, unsigned short, unsigned int, unsigned long, unsigned long long, or an extended unsigned integer type).
Contents
[edit] Parameters
x
-
value of unsigned integer type
s
-
number of positions to shift
[edit] Return value
The result of bitwise left-rotating x by s positions.
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_bitops |
201907L |
(C++20) | Bit operations |
[edit] Example
Run this code
#include <bit> #include <bitset> #include <cstdint> #include <iostream> int main() { using bin = std::bitset <8>; const std::uint8_t x{0b00011101}; std::cout << bin(x) << " <- x\n"; for (const int s : {0, 1, 4, 9, -1}) std::cout << bin(std::rotl(x, s)) << " <- rotl(x, " << s << ")\n"; }
Output:
00011101 <- x 00011101 <- rotl(x, 0) 00111010 <- rotl(x, 1) 11010001 <- rotl(x, 4) 00111010 <- rotl(x, 9) 10001110 <- rotl(x, -1)