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std::popcount(3) C++ Standard Libary std::popcount(3) NAME std::popcount - std::popcount Synopsis Defined in header <bit> template< class T > (since C++20) constexpr int popcount( T x ) noexcept; Returns the number of 1 bits in the value of x. 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 Return value The number of 1 bits in the value of x. Notes Feature-test macro: __cpp_lib_bitops Example // Run this code #include <bit> #include <bitset> #include <cstdint> #include <iostream> int main() { for (const std::uint8_t i : { 0, 0b11111111, 0b00011101 }) { std::cout << "popcount( " << std::bitset<8>(i) << " ) = " << std::popcount(i) << '\n'; } } Output: popcount( 00000000 ) = 0 popcount( 11111111 ) = 8 popcount( 00011101 ) = 4 See also countl_zero counts the number of consecutive 0 bits, starting from the most (C++20) significant bit (function template) countl_one counts the number of consecutive 1 bits, starting from the most (C++20) significant bit (function template) countr_zero counts the number of consecutive 0 bits, starting from the least (C++20) significant bit (function template) countr_one counts the number of consecutive 1 bits, starting from the least (C++20) significant bit (function template) has_single_bit checks if a number is an integral power of two (C++20) (function template) count returns the number of bits set to true (public member function of std::bitset<N>) all any checks if all, any or none of the bits are set to true none (public member function of std::bitset<N>) (C++11) http://cppreference.com 2022.07.31 std::popcount(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | Output: | See also
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