Defined in header <iterator> | ||
|---|---|---|
template<class I>
concept input_iterator =
std::input_or_output_iterator<I> &&
std::indirectly_readable<I> &&
requires { typename /*ITER_CONCEPT*/<I>; } &&
std::derived_from</*ITER_CONCEPT*/<I>, std::input_iterator_tag>;
| (since C++20) |
The input_iterator concept is a refinement of input_or_output_iterator, adding the requirement that the referenced values can be read (via indirectly_readable) and the requirement that the iterator concept tag be present.
Definition of this concept is specified via an exposition-only alias template /*ITER_CONCEPT*/.
In order to determine /*ITER_CONCEPT*/<I>, let ITER_TRAITS<I> denote I if the specialization std::iterator_traits<I> is generated from the primary template, or std::iterator_traits<I> otherwise:
ITER_TRAITS<I>::iterator_concept is valid and names a type, /*ITER_CONCEPT*/<I> denotes the type. ITER_TRAITS<I>::iterator_category is valid and names a type, /*ITER_CONCEPT*/<I> denotes the type. std::iterator_traits<I> is generated from the primary template, /*ITER_CONCEPT*/<I> denotes std::random_access_iterator_tag. /*ITER_CONCEPT*/<I> does not denote a type and results in a substitution failure. Unlike the LegacyInputIterator requirements, the input_iterator concept does not require equality_comparable, since input iterators are typically compared with sentinels.
|
(C++20) | specifies that objects of a type can be incremented and dereferenced (concept) |
|
(C++20) | specifies that an input_iterator is a forward iterator, supporting equality comparison and multi-pass (concept) |
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