[alg.find.end]

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

## 26.6 Non-modifying sequence operations [[alg.nonmodifying]](alg.nonmodifying#alg.find.end)

### 26.6.8 Find end [alg.find.end]

[ð](#lib:find_end)

`template<class ForwardIterator1, class ForwardIterator2>
  constexpr ForwardIterator1
    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
             ForwardIterator2 first2, ForwardIterator2 last2);
template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2>
  ForwardIterator1
    find_end(ExecutionPolicy&& exec,
             ForwardIterator1 first1, ForwardIterator1 last1,
             ForwardIterator2 first2, ForwardIterator2 last2);

template<class ForwardIterator1, class ForwardIterator2,
         class BinaryPredicate>
  constexpr ForwardIterator1
    find_end(ForwardIterator1 first1, ForwardIterator1 last1,
             ForwardIterator2 first2, ForwardIterator2 last2,
             BinaryPredicate pred);
template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2,
         class BinaryPredicate>
  ForwardIterator1
    find_end(ExecutionPolicy&& exec,
             ForwardIterator1 first1, ForwardIterator1 last1,
             ForwardIterator2 first2, ForwardIterator2 last2,
             BinaryPredicate pred);

template<[forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11 Concept forward_­iterator [iterator.concept.forward]") I1, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<I1> S1, [forward_iterator](iterator.concept.forward#concept:forward_iterator "24.3.4.11 Concept forward_­iterator [iterator.concept.forward]") I2, [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<I2> S2,
         class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
  requires [indirectly_comparable](alg.req.ind.cmp#concept:indirectly_comparable "24.3.7.5 Concept indirectly_­comparable [alg.req.ind.cmp]")<I1, I2, Pred, Proj1, Proj2>
  constexpr subrange<I1>
    ranges::find_end(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                     Proj1 proj1 = {}, Proj2 proj2 = {});
template<[forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]") R1, [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]") R2,
         class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
  requires [indirectly_comparable](alg.req.ind.cmp#concept:indirectly_comparable "24.3.7.5 Concept indirectly_­comparable [alg.req.ind.cmp]")<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
  constexpr borrowed_subrange_t<R1>
    ranges::find_end(R1&& r1, R2&& r2, Pred pred = {},
                     Proj1 proj1 = {}, Proj2 proj2 = {});

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]") I1, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<I1> S1,
         [random_access_iterator](iterator.concept.random.access#concept:random_access_iterator "24.3.4.13 Concept random_­access_­iterator [iterator.concept.random.access]") I2, [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<I2> S2,
         class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
  requires [indirectly_comparable](alg.req.ind.cmp#concept:indirectly_comparable "24.3.7.5 Concept indirectly_­comparable [alg.req.ind.cmp]")<I1, I2, Pred, Proj1, Proj2>
  subrange<I1>
    ranges::find_end(Ep&& exec, I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {},
                     Proj1 proj1 = {}, Proj2 proj2 = {});
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]") R1, [sized-random-access-range](range.refinements#concept:sized-random-access-range "25.4.6 Other range refinements [range.refinements]") R2,
         class Pred = ranges::equal_to, class Proj1 = identity, class Proj2 = identity>
  requires [indirectly_comparable](alg.req.ind.cmp#concept:indirectly_comparable "24.3.7.5 Concept indirectly_­comparable [alg.req.ind.cmp]")<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2>
  borrowed_subrange_t<R1>
    ranges::find_end(Ep&& exec, R1&& r1, R2&& r2, Pred pred = {},
                     Proj1 proj1 = {}, Proj2 proj2 = {});
`

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L5176)

Let:

- [(1.1)](#1.1)

pred be equal_to{} for the overloads with no parameter pred;

- [(1.2)](#1.2)

E be:
  * [(1.2.1)](#1.2.1)

pred(*(i + n), *(first2 + n)) for the overloads in namespace std;

  * [(1.2.2)](#1.2.2)

invoke(pred, invoke(proj1, *(i + n)), invoke(proj2, *(first2 + n))) for the overloads in namespace ranges;

- [(1.3)](#1.3)

i be last1 if [first2, last2) is empty,
 or if (last2 - first2) > (last1 - first1) is true,
 or if there is no iterator
 in the range [first1, last1 - (last2 - first2))
 such that for every non-negative integer n < (last2 - first2), E is true[.](#1.sentence-1)
  Otherwise i is the last such iterator
 in [first1, last1 - (last2 - first2))[.](#1.3.sentence-2)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L5203)

*Returns*: 

- [(2.1)](#2.1)

  i for the overloads in namespace std[.](#2.1.sentence-1)

- [(2.2)](#2.2)

  {i, i + (i == last1 ? 0 : last2 - first2)} for the overloads in namespace ranges[.](#2.2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L5211)

*Complexity*: At most(last2 - first2) * (last1 - first1 - (last2 - first2) + 1) applications of the corresponding predicate and any projections[.](#3.sentence-1)
