[alg.req.mergeable]

# 24 Iterators library [[iterators]](./#iterators)

## 24.3 Iterator requirements [[iterator.requirements]](iterator.requirements#alg.req.mergeable)

### 24.3.7 Common algorithm requirements [[alg.req]](alg.req#mergeable)

#### 24.3.7.7 Concept mergeable [alg.req.mergeable]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iterators.tex#L2705)

The [mergeable](#concept:mergeable "24.3.7.7 Concept mergeable [alg.req.mergeable]") concept specifies the requirements of algorithms
that merge sorted sequences into an output sequence by copying elements[.](#1.sentence-1)

template<class I1, class I2, class Out, class R = ranges::less, class P1 = identity, class P2 = identity>concept [mergeable](#concept:mergeable "24.3.7.7 Concept mergeable [alg.req.mergeable]") =[input_iterator](iterator.concept.input#concept:input_iterator "24.3.4.9 Concept input_­iterator [iterator.concept.input]")<I1> &&[input_iterator](iterator.concept.input#concept:input_iterator "24.3.4.9 Concept input_­iterator [iterator.concept.input]")<I2> &&[weakly_incrementable](iterator.concept.winc#concept:weakly_incrementable "24.3.4.4 Concept weakly_­incrementable [iterator.concept.winc]")<Out> &&[indirectly_copyable](alg.req.ind.copy#concept:indirectly_copyable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]")<I1, Out> &&[indirectly_copyable](alg.req.ind.copy#concept:indirectly_copyable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]")<I2, Out> &&[indirect_strict_weak_order](indirectcallable.indirectinvocable#concept:indirect_strict_weak_order "24.3.6.3 Indirect callables [indirectcallable.indirectinvocable]")<R, projected<I1, P1>, projected<I2, P2>>;