std::counted_iterator<I>::counted_iterator

 

C++

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Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

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Technical specifications

Symbols index

External libraries

 

Iterator library

Iterator concepts
indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) input_or_output_iterator (C++20) sentinel_for (C++20) sized_sentinel_for (C++20)	input_iterator (C++20) output_iterator (C++20) forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
Iterator primitives
iterator_traits input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20) iterator (deprecated in C++17)	incrementable_traits (C++20) indirectly_readable_traits (C++20) iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(C++20)(C++20)
Algorithm concepts and utilities
Indirect callable concepts
indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20)   indirect_unary_predicate (C++20)	indirect_binary_predicate (C++20) indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
Common algorithm requirements
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20) indirectly_copyable_storable (C++20)	indirectly_swappable (C++20) indirectly_comparable (C++20) permutable (C++20) mergeable (C++20) sortable (C++20)
Utilities
indirect_result_t (C++20)	projected (C++20)
Iterator adaptors
reverse_iterator move_iterator (C++11) move_sentinel (C++20) common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20) make_const_iterator (C++23) make_const_sentinel (C++23) back_inserter front_inserter inserter
Stream iterators
istream_iterator ostream_iterator	istreambuf_iterator ostreambuf_iterator
Iterator customization points
ranges::iter_move (C++20)
ranges::iter_swap (C++20)
Iterator operations
advance distance prev (C++11) next (C++11)	ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)
Range access
begincbegin (C++11)(C++14) endcend (C++11)(C++14) sizessize (C++17)(C++20)	rbegincrbegin (C++14)(C++14) rendcrend (C++14)(C++14) empty (C++17) data (C++17)

 

std::counted_iterator

Member functions

counted_iterator::counted_iterator (C++20)

counted_iterator::operator= (C++20)

counted_iterator::base (C++20)

counted_iterator::count (C++20)

counted_iterator::operator*counted_iterator::operator-> (C++20)(C++20)

counted_iterator::operator[] (C++20)

counted_iterator::operator++counted_iterator::operator++(int)counted_iterator::operator+counted_iterator::operator+=counted_iterator::operator--counted_iterator::operator--(int)counted_iterator::operator-counted_iterator::operator-= (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

Non-member functions

operator==operator<=> (C++20)(C++20)

operator==(default_sentinel_t) (C++20)

operator+ (C++20)

operator- (C++20)

operator-(default_sentinel_t) (C++20)

iter_move (C++20)

iter_swap (C++20)

Helper classes

iterator_traits (C++20)

 

constexpr counted_iterator() requires std::default_initializable<I> = default;	(1)	(since C++20)
constexpr counted_iterator( I x, std::iter_difference_t<I> n );	(2)	(since C++20)
template< class I2 >   requires std::convertible_to<const I2&, I>     constexpr counted_iterator( const counted_iterator<I2>& other );	(3)	(since C++20)

Constructs a new iterator adaptor.

1) Default constructor. Value-initializes the underlying iterator and initialized the underlying length with ​0​. Operations on the resulting iterator have defined behavior if and only if the corresponding operations on a value-initialized I also have defined behavior.

2) The underlying iterator is initialized with std::move(x) and the underlying length is initialized with n. The behavior is undefined if n is negative.

3) The underlying iterator and length are initialized with those of other.

Parameters

x	-	iterator to adapt
n	-	distance to the end
other	-	iterator adaptor to convert

Example

Run this code

#include <algorithm>
#include <initializer_list>
#include <iostream>
#include <iterator>
 
int main() {
    static constexpr auto pi = {3, 1, 4, 1, 5, 9, 2};
 
    // (1) default constructor:
    constexpr std::counted_iterator<std::initializer_list<int>::iterator> i1{};
    static_assert(i1 == std::default_sentinel);
    static_assert(i1.count() == 0);
 
    // (2) initializes the iterator and length respectively:
    constexpr std::counted_iterator<std::initializer_list<int>::iterator> i2{
        pi.begin(), pi.size() - 2
    };
    static_assert(i2.count() == 5);
    static_assert(*i2 == 3 && i2[1] == 1);
 
    // (3) converting-constructor:
    std::counted_iterator<std::initializer_list<const int>::iterator> i3{i2};
 
    std::ranges::copy(i3, std::default_sentinel,
        std::ostream_iterator<const int>{std::cout, " "});
}

Output:

3 1 4 1 5

See also

operator= (C++20)

assigns another iterator adaptor (public member function)