std::basic_const_iterator

Defined in header <iterator>
template< std::input_iterator Iter > class basic_const_iterator;		(since C++23)

std::basic_const_iterator is an iterator adaptor which behaves exactly like the underlying iterator (which must be at least an LegacyInputIterator or model input_iterator), except that dereferencing converts the value returned by the underlying iterator as immutable. Specializations of std::basic_const_iterator are constant iterators, that is, the iterator can never be used as an output iterator because modifying elements is not allowed.

Member types

Member type	Definition
iterator_category	If Iter models forward_iterator: member iterator_category is the same type as std::iterator_traits<Iter>::iterator_category. Otherwise, there is no member iterator_category.
iterator_concept	std::contiguous_iterator_tag, if Iter models contiguous_iterator; std::random_access_iterator_tag, if Iter models random_access_iterator; std::bidirectional_iterator_tag, if Iter models bidirectional_iterator; std::forward_iterator_tag, if Iter models forward_iterator; std::input_iterator_tag otherwise.
value_type	std::iter_value_t<Iter>
difference_type	std::iter_difference_t<Iter>
reference (private)	std::iter_const_reference_t<Iter>. (exposition-only member type*)

Member objects

Member name	Definition
current (private)	the underlying iterator from which base() copies or moves (exposition-only member object*)

Member functions

(constructor)	constructs a new iterator adaptor (public member function)
operator=	assigns another iterator adaptor (public member function)
base	accesses the underlying iterator (public member function)
operator*operator->	accesses the pointed-to element (public member function)
operator[]	accesses an element by index (public member function)
operator++operator++(int)operator+=operator+operator--operator--(int)operator-=operator-	advances or decrements the iterator (public member function)

Non-member functions

operator==operator<operator<=operator>operator>=operator<=> (C++23)	compares the underlying iterators (function template)
operator+ (C++23)	advances the iterator (function template)
operator- (C++23)	computes the distance between two iterator adaptors (function template)
iter_move (C++23)	casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function)

Helper classes

std::common_type<std::basic_const_iterator> (C++23)

determines the common type of an iterator and an adapted basic_const_iterator type (class template specialization)

Helper alias templates

template< std::input_iterator I > using const_iterator = /* see description */;		(since C++23)

If I models constant-iterator (an exposition-only concept), then const_iterator<I> denotes a type I. Otherwise, basic_const_iterator<I>.

template< std::semiregular S > using const_sentinel = /* see description */;		(since C++23)

If S models input_iterator, then const_sentinel<S> denotes a type const_iterator<S>. Otherwise, S.

Helper function templates

template< std::input_iterator T > constexpr const_iterator<T> make_const_iterator( I it ) { return it; }		(since C++23)
template< std::semiregular S > constexpr const_sentinel<S> make_const_sentinel( S s ) { return s; }		(since C++23)

Example

This section is incomplete Reason: example