operator+(std::counted_iterator)

 

C++

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自立实现与有宿主实现

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具名要求

功能特性测试宏(C++20)

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符号索引

外部库

 

迭代器库

迭代器概念
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)
迭代器原语
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 (C++17 弃用) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
算法概念与工具
间接可调用概念
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)
常用算法要求
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)
工具
indirect_result_t (C++20)	projected (C++20)	projected_value_t (C++26)
迭代器适配器
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)
流迭代器 istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	迭代器定制点 ranges::iter_move (C++20) ranges::iter_swap (C++20)
迭代器操作 advance distance prev (C++11)   next (C++11) ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)	范围访问 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)

 

std::counted_iterator

成员函数

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-=

非成员函数

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)

辅助类

iterator_traits<std::counted_iterator> (C++20)

 

friendconstexpr counted_iterator operator+(     std::iter_difference_t<I> n, const counted_iterator& x )         requires std::random_access_iterator<I>;		(C++20 起)

返回前进 n 个位置的迭代器适配器。若 n 大于 x 内记录的长度（即若 x + n 导致未定义行为）则行为未定义。

此函数对常规的无限定或有限定查找不可见，而只能在 std::counted_iterator<I> 为实参的关联类时由实参依赖查找找到。

参数

n	-	要增加迭代器的位置数
x	-	要增加的迭代器

返回值

等于 x + n 的迭代器适配器。

示例

运行此代码

#include <iostream>#include <iterator>#include <list>#include <vector>   int main(){std::vector v{0, 1, 2, 3, 4, 5};std::counted_iterator<std::vector<int>::iterator> p{v.begin()+1, 4};std::cout<<"*p:"<<*p <<", count:"<< p.count()<<'\n';std::counted_iterator<std::vector<int>::iterator> q{2+ p};std::cout<<"*q:"<<*q <<", count:"<< q.count()<<'\n';   std::list l{6, 7, 8, 9};std::counted_iterator<std::list<int>::iterator> r{l.begin(), 3};std::cout<<"*r:"<<*r <<", count:"<< r.count()<<'\n';// auto s { 2 + r }; // 错误：底层迭代器不实现 std::random_access_iterator}

输出：

*p:1, count:4 *q:3, count:2 *r:6, count:3

参阅

operator++operator++(int)operator+=operator+operator--operator--(int)operator-=operator-	推进或回退 counted_iterator (公开成员函数)
operator- (C++20)	计算两个迭代器适配器间的距离 (函数模板)
operator-(std::default_sentinel_t) (C++20)	计算到末尾的有符号距离 (函数模板)