std::popcount
Defined in header <bit> |
||
---|---|---|
template< class T > constexpr int popcount( T x ) noexcept; |
(since C++20) |
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 testing macro: __cpp_lib_bitops
.
Example
#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
(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 consecutive 1 bits, starting from the least significant bit (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> ) |
|
(C++11)
|
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/popcount