std::move_iterator<Iter>::运算符*,->

 

C++

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具名要求

Feature test macros (C++20)

语言支持库

Concepts library (C++20)

诊断库

内存管理库

Metaprogramming library (C++11)

通用工具库

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Ranges library (C++20)

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Filesystem library (C++17)

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Execution control library (C++26)

技术规范

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 (在 C++17 中已弃用) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
算法概念和工具
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	迭代器自定义点 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::move_iterator

成员函数

move_iterator::move_iterator

move_iterator::operator=

move_iterator::base

move_iterator::operator*move_iterator::operator->

move_iterator::operator[]

move_iterator::operator++move_iterator::operator+move_iterator::operator+=move_iterator::operator--move_iterator::operator-move_iterator::operator-=

非成员函数

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

operator==(move_sentinel) (C++20)

operator+

operator-

operator-(move_sentinel) (C++20)

iter_move (C++20)

iter_swap (C++20)

make_move_iterator (C++11)

 

reference operator*() const;	(1)	(自 C++11 起) (constexpr 自 C++17 起)
pointer operator->() const;	(2)	(自 C++11 起) (constexpr 自 C++17 起) (在 C++20 中已弃用)

返回当前元素的右值引用或指针。

返回值

1) static_cast<reference>(*current )(直到 C++20)ranges::iter_move(current )(自 C++20 起)

2) current

注释

operator-> 已被弃用，因为解引用其结果可能会产生左值。这可能会导致意外行为。

示例

运行此代码

#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
void print(auto rem, const auto& v)
{
    for (std::cout << rem; const auto& e : v)
        std::cout << std::quoted(e) << ' ';
    std::cout << '\n';
}
 
int main()
{
    std::vector<std::string> p{"alpha", "beta", "gamma", "delta"}, q;
    print("1) p: ", p);
    for (std::move_iterator it{p.begin()}, end{p.end()}; it != end; ++it)
    {
        it->push_back('!'); // calls -> string::push_back(char)
        q.emplace_back(*it); // *it <- overload (1)
    }
    print("2) p: ", p);
    print("3) q: ", q);
 
    std::vector v{1, 2, 3};
    std::move_iterator it{v.begin()};
    // *it = 13; // error: using rvalue as lvalue
}

可能的输出

1) p: "alpha" "beta" "gamma" "delta"
2) p: "" "" "" ""
3) q: "alpha!" "beta!" "gamma!" "delta!"

缺陷报告

以下行为变更缺陷报告被追溯应用于先前发布的 C++ 标准。

DR	应用于	已发布行为	正确行为
LWG 2106	C++11	operator* 会返回一个悬空的 引用，如果 *current 产生一个 prvalue	返回对象 在这种情况下

参见

operator[]

通过索引访问元素 (公共成员函数)