std::rotl

 

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Defined in header <bit>
template< class T > constexpr T rotl( T x, int s ) noexcept;		(since C++20)

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).

Parameters

x	-	value of unsigned integer type
s	-	number of positions to shift

Return value

The result of bitwise left-rotating x by s positions.

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_bitops	201907L	(C++20)	Bit operations

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)

See also

rotr (C++20)	computes the result of bitwise right-rotation (function template)
operator<<=operator>>=operator<<operator>>	performs binary shift left and shift right (public member function of std::bitset<N>)