[partial.sum]

# 26 Algorithms library [[algorithms]](./#algorithms)

## 26.10 Generalized numeric operations [[numeric.ops]](numeric.ops#partial.sum)

### 26.10.7 Partial sum [partial.sum]

[🔗](#lib: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);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L12657)

*Mandates*: InputIterator's value type is constructible from *first[.](#1.sentence-1)

The result of the
expression std​::​move(acc) + *i or binary_op(std​::​move(acc), *i) is implicitly convertible to InputIterator's value type[.](#1.sentence-2)

acc is writable ([[iterator.requirements.general]](iterator.requirements.general "24.3.1 General")) to result[.](#1.sentence-3)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L12665)

*Preconditions*: In the ranges [first, last] and [result, result + (last - first)]binary_op neither modifies elements
nor invalidates iterators or subranges[.](#2.sentence-1)[208](#footnote-208 "The use of fully closed ranges is intentional.")

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L12674)

*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[.](#3.sentence-1)

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))[.](#3.sentence-2)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L12686)

*Returns*: result + (last - first)[.](#4.sentence-1)

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L12690)

*Complexity*: Exactly (last - first) - 1 applications of the binary operation[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L12694)

*Remarks*: result may be equal to first[.](#6.sentence-1)

[208)](#footnote-208)[208)](#footnoteref-208)

The use of fully closed ranges is intentional[.](#footnote-208.sentence-1)