[alg.fill]

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

## 26.7 Mutating sequence operations [[alg.modifying.operations]](alg.modifying.operations#alg.fill)

### 26.7.6 Fill [alg.fill]

[🔗](#lib:fill)

`template<class ForwardIterator, class T = iterator_traits<ForwardIterator>::value_type>
  constexpr void fill(ForwardIterator first, ForwardIterator last, const T& value);
template<class ExecutionPolicy, class ForwardIterator,
         class T = iterator_traits<ForwardIterator>::value_type>
  void fill(ExecutionPolicy&& exec,
            ForwardIterator first, ForwardIterator last, const T& value);

template<class OutputIterator, class Size, class T = iterator_traits<OutputIterator>::value_type>
  constexpr OutputIterator fill_n(OutputIterator first, Size n, const T& value);
template<class ExecutionPolicy, class ForwardIterator, class Size,
         class T = iterator_traits<ForwardIterator>::value_type>
  ForwardIterator fill_n(ExecutionPolicy&& exec,
                         ForwardIterator first, Size n, const T& value);

template<class O, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<O> S, class T = iter_value_t<O>>
  requires [output_iterator](iterator.concept.output#concept:output_iterator "24.3.4.10 Concept output_­iterator [iterator.concept.output]")<O, const T&>
  constexpr O ranges::fill(O first, S last, const T& value);
template<class R, class T = range_value_t<R>>
  requires [output_range](range.refinements#concept:output_range "25.4.6 Other range refinements [range.refinements]")<R, const T&>
  constexpr borrowed_iterator_t<R> ranges::fill(R&& r, const T& value);
template<class O, class T = iter_value_t<O>>
  requires [output_iterator](iterator.concept.output#concept:output_iterator "24.3.4.10 Concept output_­iterator [iterator.concept.output]")<O, const T&>
  constexpr O ranges::fill_n(O first, iter_difference_t<O> n, const T& value);

template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1 Preamble [algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13 Concept random_­access_­iterator [iterator.concept.random.access]") O, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<O> S,
         class T = iter_value_t<O>>
  requires [indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<O, const T&>
  O ranges::fill(Ep&& exec, O first, S last, const T& value);
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1 Preamble [algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6 Other range refinements [range.refinements]") R, class T = range_value_t<R>>
  requires [indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<iterator_t<R>, const T&>
  borrowed_iterator_t<R> fill(Ep&& exec, R&& r, const T& value);
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1 Preamble [algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13 Concept random_­access_­iterator [iterator.concept.random.access]") O, class T = iter_value_t<O>>
  requires [indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<O, const T&>
  O ranges::fill_n(Ep&& exec, O first, iter_difference_t<O> n, const T& value);
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L7432)

Let N be max(0, n) for the fill_n algorithms, andlast - first for the fill algorithms[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L7436)

*Mandates*: The expression value is writable ([[iterator.requirements.general]](iterator.requirements.general "24.3.1 General")) to the output iterator[.](#2.sentence-1)

The type Size is convertible
to an integral type ([[conv.integral]](conv.integral "7.3.9 Integral conversions"), [[class.conv]](class.conv "11.4.8 Conversions"))[.](#2.sentence-2)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L7443)

*Effects*: Assigns value through all the iterators in the range [first, first + N)[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L7448)

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

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L7452)

*Complexity*: Exactly N assignments[.](#5.sentence-1)