27 Algorithms library [algorithms]

27.10 Generalized numeric operations [numeric.ops]

27.10.9 Inclusive scan [inclusive.scan]

template<class InputIterator, class OutputIterator>
  constexpr OutputIterator
    inclusive_scan(InputIterator first, InputIterator last,
                   OutputIterator result);

Effects: Equivalent to: return inclusive_scan(first, last, result, plus<>());

🔗

template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2>
  ForwardIterator2
    inclusive_scan(ExecutionPolicy&& exec,
                   ForwardIterator1 first, ForwardIterator1 last,
                   ForwardIterator2 result);

Effects: Equivalent to: return inclusive_scan(std::forward<ExecutionPolicy>(exec), first, last, result, plus<>());

🔗

template<class InputIterator, class OutputIterator, class BinaryOperation>
  constexpr OutputIterator
    inclusive_scan(InputIterator first, InputIterator last,
                   OutputIterator result, BinaryOperation binary_op);
template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2,
         class BinaryOperation>
  ForwardIterator2
    inclusive_scan(ExecutionPolicy&& exec,
                   ForwardIterator1 first, ForwardIterator1 last,
                   ForwardIterator2 result, BinaryOperation binary_op);

template<class InputIterator, class OutputIterator, class BinaryOperation, class T>
  constexpr OutputIterator
    inclusive_scan(InputIterator first, InputIterator last,
                   OutputIterator result, BinaryOperation binary_op, T init);
template<class ExecutionPolicy,
         class ForwardIterator1, class ForwardIterator2, class BinaryOperation, class T>
  ForwardIterator2
    inclusive_scan(ExecutionPolicy&& exec,
                   ForwardIterator1 first, ForwardIterator1 last,
                   ForwardIterator2 result, BinaryOperation binary_op, T init);

Let U be the value type of decltype(first).

Mandates: If init is provided, all of

(4.1)
binary_op(init, init),
(4.2)
binary_op(init, *first), and
(4.3)
binary_op(*first, *first)

are convertible to T; otherwise, binary_op(*first, *first) is convertible to U.

Preconditions:

(5.1)
If init is provided, T meets the Cpp17MoveConstructible (Table 31) requirements; otherwise, U meets the Cpp17MoveConstructible requirements.
(5.2)
binary_op neither invalidates iterators or subranges, nor modifies elements in the ranges [first, last] or [result, result + (last - first)].

Effects: For each integer K in [0, last - first) assigns through result + K the value of

(6.1)
GENERALIZED_NONCOMMUTATIVE_SUM(
binary_op, init, *(first + 0), *(first + 1), ..., *(first + K))

if init is provided, or
(6.2)
GENERALIZED_NONCOMMUTATIVE_SUM(
binary_op, *(first + 0), *(first + 1), ..., *(first + K))

otherwise.

Returns: The end of the resulting range beginning at result.

Complexity:

O (last - first)

applications of binary_op.

Remarks: result may be equal to first.

[Note 1:

The difference between exclusive_scan and inclusive_scan is that inclusive_scan includes the

i^{th}

input element in the

i^{th}

sum.

If binary_op is not mathematically associative, the behavior of inclusive_scan can be nondeterministic.

— end note]