22 General utilities library [utilities]

22.15 Bit manipulation [bit]

22.15.7 Counting [bit.count]

1
#
In the following descriptions, let N denote numeric_limits<T>​::​digits.
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template<class T> constexpr int countl_zero(T x) noexcept;
2
#
Constraints: T is an unsigned integer type ([basic.fundamental]).
3
#
Returns: The number of consecutive 0 bits in the value of x, starting from the most significant bit.
[Note 1: 
Returns N if x == 0.
— end note]
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template<class T> constexpr int countl_one(T x) noexcept;
4
#
Constraints: T is an unsigned integer type ([basic.fundamental]).
5
#
Returns: The number of consecutive 1 bits in the value of x, starting from the most significant bit.
[Note 2: 
Returns N if x == numeric_limits<T>​::​max().
— end note]
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template<class T> constexpr int countr_zero(T x) noexcept;
6
#
Constraints: T is an unsigned integer type ([basic.fundamental]).
7
#
Returns: The number of consecutive 0 bits in the value of x, starting from the least significant bit.
[Note 3: 
Returns N if x == 0.
— end note]
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template<class T> constexpr int countr_one(T x) noexcept;
8
#
Constraints: T is an unsigned integer type ([basic.fundamental]).
9
#
Returns: The number of consecutive 1 bits in the value of x, starting from the least significant bit.
[Note 4: 
Returns N if x == numeric_limits<T>​::​max().
— end note]
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template<class T> constexpr int popcount(T x) noexcept;
10
#
Constraints: T is an unsigned integer type ([basic.fundamental]).
11
#
Returns: The number of 1 bits in the value of x.