[alg.req.ind.copy]

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

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

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

#### 24.3.7.3 Concept indirectly_copyable [alg.req.ind.copy]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iterators.tex#L2613)

The [indirectly_copyable](#concept:indirectly_copyable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]") concept specifies the relationship between
an [indirectly_readable](iterator.concept.readable#concept:indirectly_readable "24.3.4.2 Concept indirectly_­readable [iterator.concept.readable]") type and an [indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]") type
between which values may be copied[.](#1.sentence-1)

template<class In, class Out>concept [indirectly_copyable](#concept:indirectly_copyable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]") =[indirectly_readable](iterator.concept.readable#concept:indirectly_readable "24.3.4.2 Concept indirectly_­readable [iterator.concept.readable]")<In> &&[indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<Out, iter_reference_t<In>>;

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iterators.tex#L2625)

The [indirectly_copyable_storable](#concept:indirectly_copyable_storable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]") concept augments[indirectly_copyable](#concept:indirectly_copyable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]") with additional requirements enabling
the transfer to be performed through an intermediate object of the[indirectly_readable](iterator.concept.readable#concept:indirectly_readable "24.3.4.2 Concept indirectly_­readable [iterator.concept.readable]") type's value type[.](#2.sentence-1)

It also requires the capability
to make copies of values[.](#2.sentence-2)

template<class In, class Out>concept [indirectly_copyable_storable](#concept:indirectly_copyable_storable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]") =[indirectly_copyable](#concept:indirectly_copyable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]")<In, Out> &&[indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<Out, iter_value_t<In>&> &&[indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<Out, const iter_value_t<In>&> &&[indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<Out, iter_value_t<In>&&> &&[indirectly_writable](iterator.concept.writable#concept:indirectly_writable "24.3.4.3 Concept indirectly_­writable [iterator.concept.writable]")<Out, const iter_value_t<In>&&> &&[copyable](concepts.object#concept:copyable "18.6 Object concepts [concepts.object]")<iter_value_t<In>> &&[constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_­from [concept.constructible]")<iter_value_t<In>, iter_reference_t<In>> &&[assignable_from](concept.assignable#concept:assignable_from "18.4.8 Concept assignable_­from [concept.assignable]")<iter_value_t<In>&, iter_reference_t<In>>;

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/iterators.tex#L2645)

Let i be a dereferenceable value of type In[.](#3.sentence-1)

In and Out model [indirectly_copyable_storable](#concept:indirectly_copyable_storable "24.3.7.3 Concept indirectly_­copyable [alg.req.ind.copy]")<In, Out> only if after the initialization of the object obj initer_value_t<In> obj(*i);obj is equal to the value previously denoted by *i[.](#3.sentence-2)

Ifiter_reference_t<In> is an rvalue reference type, the resulting state
of the value denoted by *i is
valid but unspecified ([[lib.types.movedfrom]](lib.types.movedfrom "16.4.6.17 Moved-from state of library types"))[.](#3.sentence-3)