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[alg.sort]
# 26 Algorithms library [[algorithms]](./#algorithms)
## 26.8 Sorting and related operations [[alg.sorting]](alg.sorting#alg.sort)
### 26.8.2 Sorting [alg.sort]
#### [26.8.2.1](#sort) sort [[sort]](sort)
[🔗](#lib:sort)
`template<class RandomAccessIterator>
constexpr void sort(RandomAccessIterator first, RandomAccessIterator last);
template<class ExecutionPolicy, class RandomAccessIterator>
void sort(ExecutionPolicy&& exec,
RandomAccessIterator first, RandomAccessIterator last);
template<class RandomAccessIterator, class Compare>
constexpr void sort(RandomAccessIterator first, RandomAccessIterator last,
Compare comp);
template<class ExecutionPolicy, class RandomAccessIterator, class Compare>
void sort(ExecutionPolicy&& exec,
RandomAccessIterator first, RandomAccessIterator last,
Compare comp);
template<[random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I> S, class Comp = ranges::less,
class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I, Comp, Proj>
constexpr I
ranges::sort(I first, S last, Comp comp = {}, Proj proj = {});
template<[random_access_range](range.refinements#concept:random_access_range "25.4.6Other range refinements[range.refinements]") R, class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R>, Comp, Proj>
constexpr borrowed_iterator_t<R>
ranges::sort(R&& r, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I> S,
class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I, Comp, Proj>
I ranges::sort(Ep&& exec, I first, S last, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R, class Comp = ranges::less,
class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R>, Comp, Proj>
borrowed_iterator_t<R> ranges::sort(Ep&& exec, R&& r, Comp comp = {}, Proj proj = {});
`
[1](#sort-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8795)
Let comp be less{} and proj be identity{} for the overloads with no parameters by those names[.](#sort-1.sentence-1)
[2](#sort-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8800)
*Preconditions*: For the overloads in namespace std,RandomAccessIterator meets
the [*Cpp17ValueSwappable*](swappable.requirements#:Cpp17ValueSwappable "16.4.4.3Swappable requirements[swappable.requirements]") requirements ([[swappable.requirements]](swappable.requirements "16.4.4.3Swappable requirements")) and
the type of *first meets
the [*Cpp17MoveConstructible*](utility.arg.requirements#:Cpp17MoveConstructible "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [31](utility.arg.requirements#tab:cpp17.moveconstructible "Table 31: Cpp17MoveConstructible requirements")) and[*Cpp17MoveAssignable*](utility.arg.requirements#:Cpp17MoveAssignable "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [33](utility.arg.requirements#tab:cpp17.moveassignable "Table 33: Cpp17MoveAssignable requirements")) requirements[.](#sort-2.sentence-1)
[3](#sort-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8809)
*Effects*: Sorts the elements in the range [first, last)
with respect to comp and proj[.](#sort-3.sentence-1)
[4](#sort-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8814)
*Returns*: last for the overloads in namespace ranges[.](#sort-4.sentence-1)
[5](#sort-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8818)
*Complexity*: Let N be last - first[.](#sort-5.sentence-1)
O(NlogN) comparisons and projections[.](#sort-5.sentence-2)
#### [26.8.2.2](#stable.sort) stable_sort [[stable.sort]](stable.sort)
[🔗](#lib:stable_sort)
`template<class RandomAccessIterator>
constexpr void stable_sort(RandomAccessIterator first, RandomAccessIterator last);
template<class ExecutionPolicy, class RandomAccessIterator>
void stable_sort(ExecutionPolicy&& exec,
RandomAccessIterator first, RandomAccessIterator last);
template<class RandomAccessIterator, class Compare>
constexpr void stable_sort(RandomAccessIterator first, RandomAccessIterator last,
Compare comp);
template<class ExecutionPolicy, class RandomAccessIterator, class Compare>
void stable_sort(ExecutionPolicy&& exec,
RandomAccessIterator first, RandomAccessIterator last,
Compare comp);
template<[random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I> S, class Comp = ranges::less,
class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I, Comp, Proj>
constexpr I ranges::stable_sort(I first, S last, Comp comp = {}, Proj proj = {});
template<[random_access_range](range.refinements#concept:random_access_range "25.4.6Other range refinements[range.refinements]") R, class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R>, Comp, Proj>
constexpr borrowed_iterator_t<R>
ranges::stable_sort(R&& r, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I> S,
class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I, Comp, Proj>
I ranges::stable_sort(Ep&& exec, I first, S last, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R, class Comp = ranges::less,
class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R>, Comp, Proj>
borrowed_iterator_t<R>
ranges::stable_sort(Ep&& exec, R&& r, Comp comp = {}, Proj proj = {});
`
[1](#stable.sort-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8863)
Let comp be less{} and proj be identity{} for the overloads with no parameters by those names[.](#stable.sort-1.sentence-1)
[2](#stable.sort-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8868)
*Preconditions*: For the overloads in namespace std,RandomAccessIterator meets
the [*Cpp17ValueSwappable*](swappable.requirements#:Cpp17ValueSwappable "16.4.4.3Swappable requirements[swappable.requirements]") requirements ([[swappable.requirements]](swappable.requirements "16.4.4.3Swappable requirements")) and
the type of *first meets
the [*Cpp17MoveConstructible*](utility.arg.requirements#:Cpp17MoveConstructible "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [31](utility.arg.requirements#tab:cpp17.moveconstructible "Table 31: Cpp17MoveConstructible requirements")) and[*Cpp17MoveAssignable*](utility.arg.requirements#:Cpp17MoveAssignable "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [33](utility.arg.requirements#tab:cpp17.moveassignable "Table 33: Cpp17MoveAssignable requirements")) requirements[.](#stable.sort-2.sentence-1)
[3](#stable.sort-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8877)
*Effects*: Sorts the elements in the range [first, last)
with respect to comp and proj[.](#stable.sort-3.sentence-1)
[4](#stable.sort-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8882)
*Returns*: last for the overloads in namespace ranges[.](#stable.sort-4.sentence-1)
[5](#stable.sort-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8886)
*Complexity*: Let N be last - first[.](#stable.sort-5.sentence-1)
If enough extra memory is available, Nlog(N) comparisons[.](#stable.sort-5.sentence-2)
Otherwise, at most Nlog2(N) comparisons[.](#stable.sort-5.sentence-3)
In either case, twice as many projections as the number of comparisons[.](#stable.sort-5.sentence-4)
[6](#stable.sort-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8893)
*Remarks*: Stable ([[algorithm.stable]](algorithm.stable "16.4.6.8Requirements for stable algorithms"))[.](#stable.sort-6.sentence-1)
#### [26.8.2.3](#partial.sort) partial_sort [[partial.sort]](partial.sort)
[🔗](#lib:partial_sort)
`template<class RandomAccessIterator>
constexpr void partial_sort(RandomAccessIterator first,
RandomAccessIterator middle,
RandomAccessIterator last);
template<class ExecutionPolicy, class RandomAccessIterator>
void partial_sort(ExecutionPolicy&& exec,
RandomAccessIterator first,
RandomAccessIterator middle,
RandomAccessIterator last);
template<class RandomAccessIterator, class Compare>
constexpr void partial_sort(RandomAccessIterator first,
RandomAccessIterator middle,
RandomAccessIterator last,
Compare comp);
template<class ExecutionPolicy, class RandomAccessIterator, class Compare>
void partial_sort(ExecutionPolicy&& exec,
RandomAccessIterator first,
RandomAccessIterator middle,
RandomAccessIterator last,
Compare comp);
template<[random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I> S, class Comp = ranges::less,
class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I, Comp, Proj>
constexpr I
ranges::partial_sort(I first, I middle, S last, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I> S,
class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I, Comp, Proj>
I ranges::partial_sort(Ep&& exec, I first, I middle, S last, Comp comp = {}, Proj proj = {});
`
[1](#partial.sort-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8936)
Let comp be less{} and proj be identity{} for the overloads with no parameters by those names[.](#partial.sort-1.sentence-1)
[2](#partial.sort-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8941)
*Preconditions*: [first, middle) and [middle, last) are valid ranges[.](#partial.sort-2.sentence-1)
For the overloads in namespace std,RandomAccessIterator meets
the [*Cpp17ValueSwappable*](swappable.requirements#:Cpp17ValueSwappable "16.4.4.3Swappable requirements[swappable.requirements]") requirements ([[swappable.requirements]](swappable.requirements "16.4.4.3Swappable requirements")) and
the type of *first meets
the [*Cpp17MoveConstructible*](utility.arg.requirements#:Cpp17MoveConstructible "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [31](utility.arg.requirements#tab:cpp17.moveconstructible "Table 31: Cpp17MoveConstructible requirements")) and[*Cpp17MoveAssignable*](utility.arg.requirements#:Cpp17MoveAssignable "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [33](utility.arg.requirements#tab:cpp17.moveassignable "Table 33: Cpp17MoveAssignable requirements")) requirements[.](#partial.sort-2.sentence-2)
[3](#partial.sort-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8951)
*Effects*: Places the first middle - first elements
from the range [first, last)
as sorted with respect to comp and proj into the range [first, middle)[.](#partial.sort-3.sentence-1)
The rest of the elements in the range [middle, last)
are placed in an unspecified order[.](#partial.sort-3.sentence-2)
[4](#partial.sort-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8961)
*Returns*: last for the overload in namespace ranges[.](#partial.sort-4.sentence-1)
[5](#partial.sort-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8965)
*Complexity*: Approximately (last - first) * log(middle - first) comparisons, and
twice as many projections[.](#partial.sort-5.sentence-1)
[🔗](#partial.sort-itemdecl:2)
`template<[random_access_range](range.refinements#concept:random_access_range "25.4.6Other range refinements[range.refinements]") R, class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R>, Comp, Proj>
constexpr borrowed_iterator_t<R>
ranges::partial_sort(R&& r, iterator_t<R> middle, Comp comp = {}, Proj proj = {});
`
[6](#partial.sort-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8979)
*Effects*: Equivalent to:return ranges::partial_sort(ranges::begin(r), middle, ranges::end(r), comp, proj);
[🔗](#partial.sort-itemdecl:3)
`template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R,
class Comp = ranges::less, class Proj = identity>
requires [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R>, Comp, Proj>
borrowed_iterator_t<R>
ranges::partial_sort(Ep&& exec, R&& r, iterator_t<R> middle, Comp comp = {},
Proj proj = {});
`
[7](#partial.sort-7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L8997)
*Effects*: Equivalent to:return ranges::partial_sort(std::forward<Ep>(exec), ranges::begin(r), middle,
ranges::end(r), comp, proj);
#### [26.8.2.4](#partial.sort.copy) partial_sort_copy [[partial.sort.copy]](partial.sort.copy)
[🔗](#lib:partial_sort_copy)
`template<class InputIterator, class RandomAccessIterator>
constexpr RandomAccessIterator
partial_sort_copy(InputIterator first, InputIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last);
template<class ExecutionPolicy, class ForwardIterator, class RandomAccessIterator>
RandomAccessIterator
partial_sort_copy(ExecutionPolicy&& exec,
ForwardIterator first, ForwardIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last);
template<class InputIterator, class RandomAccessIterator,
class Compare>
constexpr RandomAccessIterator
partial_sort_copy(InputIterator first, InputIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last,
Compare comp);
template<class ExecutionPolicy, class ForwardIterator, class RandomAccessIterator,
class Compare>
RandomAccessIterator
partial_sort_copy(ExecutionPolicy&& exec,
ForwardIterator first, ForwardIterator last,
RandomAccessIterator result_first,
RandomAccessIterator result_last,
Compare comp);
template<[input_iterator](iterator.concept.input#concept:input_iterator "24.3.4.9Concept input_­iterator[iterator.concept.input]") I1, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I1> S1, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I2, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I2> S2,
class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
requires [indirectly_copyable](alg.req.ind.copy#concept:indirectly_copyable "24.3.7.3Concept indirectly_­copyable[alg.req.ind.copy]")<I1, I2> && [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I2, Comp, Proj2> &&
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<Comp, projected<I1, Proj1>, projected<I2, Proj2>>
constexpr ranges::partial_sort_copy_result<I1, I2>
ranges::partial_sort_copy(I1 first, S1 last, I2 result_first, S2 result_last,
Comp comp = {}, Proj1 proj1 = {}, Proj2 proj2 = {});
template<[input_range](range.refinements#concept:input_range "25.4.6Other range refinements[range.refinements]") R1, [random_access_range](range.refinements#concept:random_access_range "25.4.6Other range refinements[range.refinements]") R2, class Comp = ranges::less,
class Proj1 = identity, class Proj2 = identity>
requires [indirectly_copyable](alg.req.ind.copy#concept:indirectly_copyable "24.3.7.3Concept indirectly_­copyable[alg.req.ind.copy]")<iterator_t<R1>, iterator_t<R2>> &&
[sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R2>, Comp, Proj2> &&
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<Comp, projected<iterator_t<R1>, Proj1>,
projected<iterator_t<R2>, Proj2>>
constexpr ranges::partial_sort_copy_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>>
ranges::partial_sort_copy(R1&& r, R2&& result_r, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I1, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I1> S1,
[random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I2, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I2> S2,
class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
requires [indirectly_copyable](alg.req.ind.copy#concept:indirectly_copyable "24.3.7.3Concept indirectly_­copyable[alg.req.ind.copy]")<I1, I2> && [sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<I2, Comp, Proj2> &&
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<Comp, projected<I1, Proj1>, projected<I2, Proj2>>
ranges::partial_sort_copy_result<I1, I2>
ranges::partial_sort_copy(Ep&& exec, I1 first, S1 last, I2 result_first, S2 result_last,
Comp comp = {}, Proj1 proj1 = {},
Proj2 proj2 = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R1, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R2,
class Comp = ranges::less, class Proj1 = identity, class Proj2 = identity>
requires [indirectly_copyable](alg.req.ind.copy#concept:indirectly_copyable "24.3.7.3Concept indirectly_­copyable[alg.req.ind.copy]")<iterator_t<R1>, iterator_t<R2>> &&
[sortable](alg.req.sortable#concept:sortable "24.3.7.8Concept sortable[alg.req.sortable]")<iterator_t<R2>, Comp, Proj2> &&
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<Comp, projected<iterator_t<R1>, Proj1>,
projected<iterator_t<R2>, Proj2>>
ranges::partial_sort_copy_result<borrowed_iterator_t<R1>, borrowed_iterator_t<R2>>
ranges::partial_sort_copy(Ep&& exec, R1&& r, R2&& result_r, Comp comp = {},
Proj1 proj1 = {}, Proj2 proj2 = {});
`
[1](#partial.sort.copy-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9076)
Let N be min(last - first, result_last - result_first)[.](#partial.sort.copy-1.sentence-1)
Let comp be less{}, andproj1 and proj2 be identity{} for the overloads with no parameters by those names[.](#partial.sort.copy-1.sentence-2)
[2](#partial.sort.copy-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9082)
*Mandates*: For the overloads in namespace std,
the expression *first is writable ([[iterator.requirements.general]](iterator.requirements.general "24.3.1General")) to result_first[.](#partial.sort.copy-2.sentence-1)
[3](#partial.sort.copy-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9088)
*Preconditions*: For the overloads in namespace std,RandomAccessIterator meets
the [*Cpp17ValueSwappable*](swappable.requirements#:Cpp17ValueSwappable "16.4.4.3Swappable requirements[swappable.requirements]") requirements ([[swappable.requirements]](swappable.requirements "16.4.4.3Swappable requirements")),
the type of *result_first meets
the [*Cpp17MoveConstructible*](utility.arg.requirements#:Cpp17MoveConstructible "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [31](utility.arg.requirements#tab:cpp17.moveconstructible "Table 31: Cpp17MoveConstructible requirements")) and[*Cpp17MoveAssignable*](utility.arg.requirements#:Cpp17MoveAssignable "16.4.4.2Template argument requirements[utility.arg.requirements]") (Table [33](utility.arg.requirements#tab:cpp17.moveassignable "Table 33: Cpp17MoveAssignable requirements")) requirements[.](#partial.sort.copy-3.sentence-1)
[4](#partial.sort.copy-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9097)
For iterators a1 and b1 in [first, last), and
iterators x2 and y2 in [result_first, result_last),
after evaluating the assignment *y2 = *b1, let E be the value ofbool(invoke(comp, invoke(proj1, *a1), invoke(proj2, *y2))).
Then, after evaluating the assignment *x2 = *a1, E is equal tobool(invoke(comp, invoke(proj2, *x2), invoke(proj2, *y2))).
[*Note [1](#partial.sort.copy-note-1)*:
Writing a value from the input range into the output range does not affect
how it is ordered by comp and proj1 or proj2[.](#partial.sort.copy-4.sentence-2)
— *end note*]
[5](#partial.sort.copy-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9113)
*Effects*: Places the first N elements
as sorted with respect to comp and proj2 into the range [result_first, result_first + N)[.](#partial.sort.copy-5.sentence-1)
[6](#partial.sort.copy-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9119)
*Returns*:
- [(6.1)](#partial.sort.copy-6.1)
result_first + N for the overloads in namespace std[.](#partial.sort.copy-6.1.sentence-1)
- [(6.2)](#partial.sort.copy-6.2)
{last, result_first + N} for
the overloads in namespace ranges[.](#partial.sort.copy-6.2.sentence-1)
[7](#partial.sort.copy-7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9129)
*Complexity*: Approximately (last - first) * log N comparisons,
and twice as many projections[.](#partial.sort.copy-7.sentence-1)
#### [26.8.2.5](#is.sorted) is_sorted [[is.sorted]](is.sorted)
[🔗](#lib:is_sorted)
`template<class ForwardIterator>
constexpr bool is_sorted(ForwardIterator first, ForwardIterator last);
`
[1](#is.sorted-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9144)
*Effects*: Equivalent to: return is_sorted_until(first, last) == last;
[🔗](#lib:is_sorted_)
`template<class ExecutionPolicy, class ForwardIterator>
bool is_sorted(ExecutionPolicy&& exec,
ForwardIterator first, ForwardIterator last);
`
[2](#is.sorted-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9157)
*Effects*: Equivalent to:return is_sorted_until(std::forward<ExecutionPolicy>(exec), first, last) == last;
[🔗](#lib:is_sorted__)
`template<class ForwardIterator, class Compare>
constexpr bool is_sorted(ForwardIterator first, ForwardIterator last,
Compare comp);
`
[3](#is.sorted-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9173)
*Effects*: Equivalent to: return is_sorted_until(first, last, comp) == last;
[🔗](#lib:is_sorted___)
`template<class ExecutionPolicy, class ForwardIterator, class Compare>
bool is_sorted(ExecutionPolicy&& exec,
ForwardIterator first, ForwardIterator last,
Compare comp);
`
[4](#is.sorted-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9188)
*Effects*: Equivalent to:return is_sorted_until(std::forward<ExecutionPolicy>(exec), first, last, comp) == last;
[🔗](#lib:is_sorted____)
`template<[forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11Concept forward_­iterator[iterator.concept.forward]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I> S, class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<I, Proj>> Comp = ranges::less>
constexpr bool ranges::is_sorted(I first, S last, Comp comp = {}, Proj proj = {});
template<[forward_range](range.refinements#concept:forward_range "25.4.6Other range refinements[range.refinements]") R, class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<iterator_t<R>, Proj>> Comp = ranges::less>
constexpr bool ranges::is_sorted(R&& r, Comp comp = {}, Proj proj = {});
`
[5](#is.sorted-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9207)
*Effects*: Equivalent to:return ranges::is_sorted_until(first, last, comp, proj) == last;
[🔗](#is.sorted-itemdecl:6)
`template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I> S,
class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<I, Proj>> Comp = ranges::less>
bool ranges::is_sorted(Ep&& exec, I first, S last, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R, class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<iterator_t<R>, Proj>> Comp = ranges::less>
bool ranges::is_sorted(Ep&& exec, R&& r, Comp comp = {}, Proj proj = {});
`
[6](#is.sorted-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9224)
*Effects*: Equivalent to:return ranges::is_sorted_until(std::forward<Ep>(exec), first, last, comp, proj) == last;
[🔗](#lib:is_sorted_until)
`template<class ForwardIterator>
constexpr ForwardIterator
is_sorted_until(ForwardIterator first, ForwardIterator last);
template<class ExecutionPolicy, class ForwardIterator>
ForwardIterator
is_sorted_until(ExecutionPolicy&& exec,
ForwardIterator first, ForwardIterator last);
template<class ForwardIterator, class Compare>
constexpr ForwardIterator
is_sorted_until(ForwardIterator first, ForwardIterator last,
Compare comp);
template<class ExecutionPolicy, class ForwardIterator, class Compare>
ForwardIterator
is_sorted_until(ExecutionPolicy&& exec,
ForwardIterator first, ForwardIterator last,
Compare comp);
template<[forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11Concept forward_­iterator[iterator.concept.forward]") I, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7Concept sentinel_­for[iterator.concept.sentinel]")<I> S, class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<I, Proj>> Comp = ranges::less>
constexpr I ranges::is_sorted_until(I first, S last, Comp comp = {}, Proj proj = {});
template<[forward_range](range.refinements#concept:forward_range "25.4.6Other range refinements[range.refinements]") R, class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<iterator_t<R>, Proj>> Comp = ranges::less>
constexpr borrowed_iterator_t<R>
ranges::is_sorted_until(R&& r, Comp comp = {}, Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13Concept random_­access_­iterator[iterator.concept.random.access]") I, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8Concept sized_­sentinel_­for[iterator.concept.sizedsentinel]")<I> S,
class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<I, Proj>> Comp = ranges::less>
I ranges::is_sorted_until(Ep&& exec, I first, S last, Comp comp = {},
Proj proj = {});
template<[execution-policy](algorithms.parallel.defns#concept:execution-policy "26.3.1Preamble[algorithms.parallel.defns]") Ep, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6Other range refinements[range.refinements]") R, class Proj = identity,
[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3Indirect callables[indirectcallable.indirectinvocable]")<projected<iterator_t<R>, Proj>> Comp = ranges::less>
borrowed_iterator_t<R>
ranges::is_sorted_until(Ep&& exec, R&& r, Comp comp = {}, Proj proj = {});
`
[7](#is.sorted-7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9272)
Let comp be less{} and proj be identity{} for the overloads with no parameters by those names[.](#is.sorted-7.sentence-1)
[8](#is.sorted-8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9277)
*Returns*: The last iterator i in [first, last]
for which the range [first, i)
is sorted with respect to comp and proj[.](#is.sorted-8.sentence-1)
[9](#is.sorted-9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L9283)
*Complexity*: Linear[.](#is.sorted-9.sentence-1)