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std::countl_one(3)	       C++ Standard Libary	      std::countl_one(3)

NAME
     std::countl_one - std::countl_one

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

	Returns  the  number  of  consecutive  1 ("one") bits in the value of x,
     starting from
	the most significant bit ("left").

	This overload participates in overload resolution only if T  is  an  un-
     signed 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 consecutive 1 bits in the value of x,  starting  from  the
     most
	significant bit.

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()
      {
	  for (const std::uint8_t i : {0, 0b11111111, 0b01111111, 0b11100011})
	      std::cout << "countl_one( " << std::bitset<8>(i) << " ) = "
			<< std::countl_one(i) << '\n';
      }

Output:
      countl_one( 00000000 ) = 0
      countl_one( 11111111 ) = 8
      countl_one( 01111111 ) = 0
      countl_one( 11100011 ) = 3

See also
	countl_zero	counts	the  number of consecutive 0 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)
	popcount       counts the number of 1 bits in an unsigned integer
	(C++20)        (function template)
	has_single_bit checks if a number is an integral power of 2
	(C++20)        (function template)
	count	       returns the number of bits set to true
		       (public member function of std::bitset<N>)
	all	       checks if all, any or none of the bits are set to true
	any	       (public member function of std::bitset<N>)
	none

http://cppreference.com 	   2024.06.10		      std::countl_one(3)
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