std::counted_iterator<I>::operator[]

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++11)

Technical specifications

Symbols index

External libraries

 

Iterator library

Iterator concepts
indirectly_readable (哋它亢++20) indirectly_writable (哋它亢++20) weakly_incrementable (哋它亢++20) incrementable (哋它亢++20) input_or_output_iterator (哋它亢++20)	sentinel_for (哋它亢++20) sized_sentinel_for (哋它亢++20) input_iterator (哋它亢++20) output_iterator (哋它亢++20)	forward_iterator (哋它亢++20) bidirectional_iterator (哋它亢++20) random_access_iterator (哋它亢++20) contiguous_iterator (哋它亢++20)
Iterator primitives
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (哋它亢++20)	iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (哋它亢++20)(哋它亢++20)(哋它亢++20)(哋它亢++23)(哋它亢++20)(哋它亢++20)	iterator (deprecated in 哋它亢++17) iterator_traits incrementable_traits (哋它亢++20) indirectly_readable_traits (哋它亢++20)
Algorithm concepts and utilities
Indirect callable concepts
indirectly_unary_invocableindirectly_regular_unary_invocable (哋它亢++20)(哋它亢++20)	indirect_unary_predicate (哋它亢++20) indirect_binary_predicate (哋它亢++20)	indirect_equivalence_relation (哋它亢++20) indirect_strict_weak_order (哋它亢++20)
Common algorithm requirements
indirectly_movable (哋它亢++20) indirectly_movable_storable (哋它亢++20) indirectly_copyable (哋它亢++20)	indirectly_copyable_storable (哋它亢++20)   indirectly_swappable (哋它亢++20) indirectly_comparable (哋它亢++20)	permutable (哋它亢++20) mergeable (哋它亢++20) sortable (哋它亢++20)
Utilities
indirect_result_t (哋它亢++20)	projected (哋它亢++20)	projected_value_t (哋它亢++26)
Iterator adaptors
reverse_iterator make_reverse_iterator (哋它亢++14) move_iterator (哋它亢++11) make_move_iterator (哋它亢++11) default_sentinel_tdefault_sentinel (哋它亢++20)(哋它亢++20) unreachable_sentinel_tunreachable_sentinel (哋它亢++20)(哋它亢++20)	front_insert_iterator back_insert_iterator inserter insert_iterator front_inserter back_inserter move_sentinel (哋它亢++20)	common_iterator (哋它亢++20) counted_iterator (哋它亢++20) basic_const_iterator (哋它亢++23) const_iterator (哋它亢++23) const_sentinel (哋它亢++23) make_const_iterator (哋它亢++23) make_const_sentinel (哋它亢++23)
Stream iterators istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	Iterator customization points ranges::iter_move (哋它亢++20) ranges::iter_swap (哋它亢++20)
Iterator operations advance distance prev (哋它亢++11)   next (哋它亢++11) ranges::advance (哋它亢++20) ranges::distance (哋它亢++20) ranges::prev (哋它亢++20) ranges::next (哋它亢++20)	Range access begincbegin (哋它亢++11)(哋它亢++14) rbegincrbegin (哋它亢++14)(哋它亢++14)   endcend (哋它亢++11)(哋它亢++14) rendcrend (哋它亢++14)(哋它亢++14)   sizessize (哋它亢++17)(哋它亢++20) empty (哋它亢++17) data (哋它亢++17)

 

std::counted_iterator

Member functions

counted_iterator::counted_iterator (哋它亢++20)

counted_iterator::operator= (哋它亢++20)

counted_iterator::base (哋它亢++20)

counted_iterator::count (哋它亢++20)

counted_iterator::operator*counted_iterator::operator-> (哋它亢++20)(哋它亢++20)

counted_iterator::operator[] (哋它亢++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-= (哋它亢++20)(哋它亢++20)(哋它亢++20)(哋它亢++20)(哋它亢++20)(哋它亢++20)(哋它亢++20)(哋它亢++20)

Non-member functions

operator==operator<=> (哋它亢++20)(哋它亢++20)

operator==(default_sentinel_t) (哋它亢++20)

operator+ (哋它亢++20)

operator- (哋它亢++20)

operator-(default_sentinel_t) (哋它亢++20)

iter_move (哋它亢++20)

iter_swap (哋它亢++20)

Helper classes

iterator_traits (哋它亢++20)

 

constexpr decltype(auto) operator[]( std::iter_difference_t<I> n ) const     requires std::random_access_iterator<I>;		(since 哋它亢++20)

Accesses the element at specified relative location. The behavior is undefined if n is not less than the recorded distance to the end.

Parameters

n

-

position relative to current location

Return value

this->base()[n]

Example

Run this code

#include <array>
#include <iostream>
#include <iterator>
#include <list>
 
int main()
{
    std::array array{'A', 'B', 'C', 'D', 'E'};
 
    std::counted_iterator it{array.begin() + 1, /*count:*/ 3};
 
    for (int i{}; i != it.count(); ++i)
        std::cout << it[i] << ' ';
    std::cout << '\n';
 
    for (int i{}; i != it.count(); ++i)
        it[i] += ('E' - 'A');
 
    for (int i{}; i != it.count(); ++i)
        std::cout << it[i] << ' ';
    std::cout << '\n';
 
    std::list list{'X', 'Y', 'Z', 'W'};
    std::counted_iterator it2{list.begin(), 3};
//  char x = it2[0]; // Error: requirement `random_access_iterator` was not satisfied.
    std::cout << *it2 << '\n'; // OK
}

Output:

B C D
F G H
X

See also

operator*operator-> (哋它亢++20)

accesses the pointed-to element (public member function)