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std::countr_zero

From cppreference.com
< cpp‎ | numeric
Defined in header <bit>
template<class T>
constexpr int countr_zero(T x) noexcept;
(since C++20)

Returns the number of consecutive 0 bits in the value of x, starting from the least significant bit ("right").

This overload only participates in overload resolution 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 - values of unsigned integer type

[edit] Return value

The number of consecutive 0 bits in the value of x, starting from the least significant bit.

[edit] Example

#include <bit>
#include <bitset>
#include <cstdint>
#include <initializer_list>
#include <iostream>
 
int main()
{
    for (std::uint8_t i : { 0, 0b11111111, 0b00011100 }) {
        std::cout << "countr_zero(0b" << std::bitset<8>(i) << ") = "
                  << std::countr_zero(i) << '\n';
    }
}

Output:

countr_zero(0b00000000) = 8
countr_zero(0b11111111) = 0
countr_zero(0b00011100) = 2

[edit] See also

counts the number of consecutive 0 bits, starting from the most significant bit
(function) [edit]
counts the number of consecutive 1 bits, starting from the most significant bit
(function) [edit]
counts the number of consecutive 1 bits, starting from the least significant bit
(function) [edit]
(C++20)
counts the number of 1 bits in an unsigned integer
(function) [edit]