iter_move(std::counted_iterator)

 

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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 中已棄用) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
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流迭代器 istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	迭代器定製點 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)	範圍訪問 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

成員函式

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-=

非成員函式

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)

輔助類

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

 

friend constexpr decltype(auto) iter_move( const std::counted_iterator& i )     noexcept(noexcept(ranges::iter_move(i.base())))         requires std::input_iterator<I>;		(C++20 起)

將底層迭代器解引用的結果轉換為其關聯的右值引用型別。

此函式體等價於 return ranges::iter_move(i.base());。

此函式對普通的非限定查詢或限定查詢不可見，僅當 std::counted_iterator<I> 是實參的關聯類時，才能透過實參依賴查詢找到它。

如果 i.count() 等於 ​0​，則行為未定義。

引數

i

-

源迭代器介面卡

返回值

一個右值引用或一個純右值臨時量。

複雜度

常數時間。

示例

執行此程式碼

#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
void print(auto const& rem, auto const& v)
{
    std::cout << rem << '[' << size(v) << "] {";
    for (char comma[]{0, ' ', 0}; auto const& s : v)
        std::cout << comma << std::quoted(s), *comma = ',';
    std::cout << "}\n";
}
 
int main()
{
    std::vector<std::string> p{"Alpha", "Bravo", "Charlie"}, q;
    print("p", p);
    print("q", q);
 
    using RI = std::counted_iterator<std::vector<std::string>::iterator>;
 
    for (RI iter{p.begin(), 2}; iter != std::default_sentinel; ++iter)
        q.emplace_back(/* ADL */ iter_move(iter));
 
    print("p", p);
    print("q", q);
}

可能的輸出

p[3] {"Alpha", "Bravo", "Charlie"}
q[0] {}
p[3] {"", "", "Charlie"}
q[2] {"Alpha", "Bravo"}

缺陷報告

下列更改行為的缺陷報告追溯地應用於以前出版的 C++ 標準。

缺陷報告	應用於	釋出時的行為	正確的行為
LWG 3953	C++20	返回型別曾是 std::iter_rvalue_reference_t<I>	更改為 decltype(auto)

參閱

iter_move (C++20)	將解引用物件的結果轉換為其關聯的右值引用型別 (定製點物件)
iter_swap (C++20)	交換兩個底層迭代器指向的物件 (函式模板)
move (C++11)	將引數轉換為亡值 (函式模板)
move_if_noexcept (C++11)	如果移動建構函式不丟擲異常，則將引數轉換為亡值 (函式模板)
forward (C++11)	轉發函式引數並使用型別模板引數來保留其值類別 (函式模板)
ranges::move (C++20)	將一個範圍的元素移動到一個新位置 (演算法函式物件)
ranges::move_backward (C++20)	以逆序將一個範圍的元素移動到一個新位置 (演算法函式物件)