# std::indirectly_copyable_storable

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< cpp‎ | iterator

Defined in header `<iterator>` |  |
template<class In, class Out> concept indirectly_copyable_storable = std::indirectly_copyable<In, Out> && std::indirectly_writable<Out, std::iter_value_t<In>&> && std::indirectly_writable<Out, const std::iter_value_t<In>&> && std::indirectly_writable<Out, std::iter_value_t<In>&&> && std::indirectly_writable<Out, const std::iter_value_t<In>&&> && std::copyable<std::iter_value_t<In>> && std::constructible_from<std::iter_value_t<In>, std::iter_reference_t<In>> && std::assignable_from<std::iter_value_t<In>&, std::iter_reference_t<In>>; |  | (since C++20)

The `indirectly_copyable_storable` concept specifies the relationship between an `indirectly_readable` type and an `indirectly_writable` type. In addition to `indirectly_copyable`, this concept specifies that the copy from the `indirectly_readable` type can be performed via an intermediate object.

### Semantic requirements

`In` and `Out` model std::indirectly_copyable_storable<In, Out> only if given a dereferenceable value `i` of type `In`:

- After the definition std::iter_value_t<In> obj(*i);, `obj` is equal to the value previously denoted by *i, and
- if std::iter_reference_t<In> is an rvalue reference type, *i is placed in a valid but unspecified state after the initialization of `obj`.

### Equality preservation

Expressions declared in requires-expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise).

### See also

indirectly_copyable (C++20) | specifies that values may be copied from an `indirectly_readable` type to an `indirectly_writable` type (concept)
indirectly_movable_storable (C++20) | specifies that values may be moved from an `indirectly_readable` type to an `indirectly_writable` type and that the move may be performed via an intermediate object (concept)

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