2.7 KiB
[partial.sum]
26 Algorithms library [algorithms]
26.10 Generalized numeric operations [numeric.ops]
26.10.7 Partial sum [partial.sum]
template<class InputIterator, class OutputIterator> constexpr OutputIterator partial_sum(InputIterator first, InputIterator last, OutputIterator result); template<class InputIterator, class OutputIterator, class BinaryOperation> constexpr OutputIterator partial_sum(InputIterator first, InputIterator last, OutputIterator result, BinaryOperation binary_op);
Mandates: InputIterator's value type is constructible from *first.
The result of the expression std::move(acc) + *i or binary_op(std::move(acc), *i) is implicitly convertible to InputIterator's value type.
acc is writable ([iterator.requirements.general]) to result.
Preconditions: In the ranges [first, last] and [result, result + (last - first)]binary_op neither modifies elements nor invalidates iterators or subranges.208
Effects: For a non-empty range, the function creates an accumulator acc whose type is InputIterator's value type, initializes it with *first, and assigns the result to *result.
For every iterator i in [first + 1, last) in order,acc is then modified byacc = std::move(acc) + *i or acc = binary_op(std::move(acc), *i) and the result is assigned to *(result + (i - first)).
Returns: result + (last - first).
Complexity: Exactly (last - first) - 1 applications of the binary operation.
Remarks: result may be equal to first.
The use of fully closed ranges is intentional.