# std::experimental::ranges::value_type

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< cpp‎ | experimental‎ | ranges

Defined in header `<experimental/ranges/iterator>` |  |
template< class I > struct value_type {}; | (1) |
template< class T > struct value_type<T*>; | (2) |
template< class I > requires std::is_array<I>::value struct value_type<I> : value_type<std::decay_t<I>> {}; | (3) |
template< class T > struct value_type<const T> : value_type<std::decay_t<T>> {}; | (4) |
template< class T > requires requires { typename T::value_type; } struct value_type<T>; | (5) |
template< class T > requires requires { typename T::element_type; } struct value_type<T>; | (6) |

Computes the associated value type of the type `I`, if any. Users may specialize `value_type` for a program-defined type.

1) Primary template is an empty struct.
2) Specialization for pointers. If `T` is an object type, provides a member type `type` equal to std::remove_cv_t<T>. Otherwise, there is no member `type`.
3) Specialization for array types.
4) Specialization for const-qualified types.
5) Specialization for types that define a public and accessible member type `value_type`. If `T::value_type` is an object type, provides a member type `type` equal to `T::value_type`. Otherwise, there is no member `type`.
6) Specialization for types that define a public and accessible member type `element_type` (e.g., std::shared_ptr). If `T::element_type` is an object type, provides a member type `type` equal to std::remove_cv_t<typename T::element_type>. Otherwise, there is no member `type`.

### Helper alias template

template< class T > using value_type_t = typename ranges::value_type<T>::type; |  | (ranges TS)

### Notes

If a type contains both a `value_type` member and a `element_type` member, then the specializations (5) and (6) are ambiguous.

`value_type` is intended for use with `Readable` types such as iterators. It is not intended for use with ranges.

### Example

| This section is incomplete Reason: no example

### See also

Readable | specifies that a type is readable by applying operator `*` (concept)
iterator_traits | compatibility traits class that collects an iterator’s associated types (alias template)

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