Defined in header <bit> | ||
|---|---|---|
template< class T > constexpr int countr_one( T x ) noexcept; | (since C++20) |
Returns the number of consecutive 1 bits in the value of x, starting from the least significant bit ("right").
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).
| x | - | value of unsigned integer type |
The number of consecutive 1 bits in the value of x, starting from the least significant bit.
| Feature-test macro | Value | Std | Comment |
|---|---|---|---|
__cpp_lib_bitops | 201907L | (C++20) | Bit operations |
#include <bit>
#include <bitset>
#include <cstdint>
#include <iostream>
int main()
{
for (const std::uint8_t i : {0, 0b11111111, 0b11111110, 0b11100011})
std::cout << "countr_one( " << std::bitset<8>(i) << " ) = "
<< std::countr_one(i) << '\n';
}Output:
countr_one( 00000000 ) = 0 countr_one( 11111111 ) = 8 countr_one( 11111110 ) = 0 countr_one( 11100011 ) = 2
|
(C++20) | counts the number of consecutive 0 bits, starting from the most significant bit (function template) |
|
(C++20) | counts the number of consecutive 1 bits, starting from the most significant bit (function template) |
|
(C++20) | counts the number of consecutive 0 bits, starting from the least significant bit (function template) |
|
(C++20) | counts the number of 1 bits in an unsigned integer (function template) |
|
(C++20) | checks if a number is an integral power of two (function template) |
returns the number of bits set to true (public member function of std::bitset<N>) |
|
checks if all, any or none of the bits are set to true (public member function of std::bitset<N>) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/numeric/countr_one