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

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Iterators library
Ranges library(C++20)
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Iterator library

Iterator concepts

indirectly_readable (C++20)
indirectly_writable (C++20)
weakly_incrementable (C++20)
incrementable (C++20)
is-integer-like is-signed-integer-like (C++20)(C++20)

sentinel_for (C++20)
sized_sentinel_for (C++20)
input_iterator (C++20)
output_iterator (C++20)
input_or_output_iterator (C++20)

forward_iterator (C++20)
bidirectional_iterator (C++20)
random_access_iterator (C++20)
contiguous_iterator (C++20)

Iterator primitives

input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag

(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)

iterator (deprecated in C++17)
iterator_traits
incrementable_traits (C++20)
indirectly_readable_traits (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)

(C++20)

(C++20)

(C++26)

reverse_iterator
make_reverse_iterator (C++14)
move_iterator (C++11)
make_move_iterator (C++11)
default_sentinel_tdefault_sentinel (C++20)(C++20)
unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)

front_insert_iterator
back_insert_iterator
inserter
insert_iterator
front_inserter
back_inserter
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)
make_const_iterator (C++23)
make_const_sentinel (C++23)

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)
rbegincrbegin (C++14)(C++14)

endcend (C++11)(C++14)
rendcrend (C++14)(C++14)

sizessize (C++17)(C++20)
empty (C++17)
data (C++17)

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std::counted_iterator

Member functions
counted_iterator::counted_iterator
counted_iterator::operator=
counted_iterator::base
counted_iterator::count
counted_iterator::operator*counted_iterator::operator->
counted_iterator::operator[]
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-=
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<std::counted_iterator> (C++20)

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

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

[edit]Parameters

position relative to current location

[edit]Return value

this->base()[n]

[edit]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}