std::move_iterator<Iter>::operator*,->

 

C++

语言

标准库头文件

自立与有宿主实现

具名要求

语言支持库

概念库 (C++20)

诊断库

工具库

字符串库

容器库

迭代器库

范围库 (C++20)

算法库

数值库

本地化库

输入/输出库

文件系统库 (C++17)

正则表达式库 (C++11)

原子操作库 (C++11)

线程支持库 (C++11)

技术规范

 

迭代器库

迭代器概念
indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) input_or_output_iterator (C++20) sentinel_for (C++20) sized_sentinel_for (C++20)	input_iterator (C++20) 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
iterator_traits input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20) iterator (C++17 中弃用)	incrementable_traits (C++20) indirectly_readable_traits (C++20) iter_value_titer_difference_titer_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++20)(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	projected
迭代器适配器
reverse_iterator move_iterator (C++11) move_sentinel (C++20) common_iterator (C++20) counted_iterator (C++20) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20) back_inserter front_inserter inserter
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) endcend (C++11)(C++14) sizessize (C++17)(C++20)	rbegincrbegin (C++14)(C++14) rendcrend (C++14)(C++14) 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<=> (C++20 前)(C++20)

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

operator+

operator-

operator-(move_sentinel) (C++20)

iter_move (C++20)

iter_swap (C++20)

 

	(1)
reference operator* () const;			(C++11 起) (C++17 前)
constexpr reference operator* () const;			(C++17 起)
		(2)
pointer operator->() const;				(C++11 起) (C++17 前)
constexpr pointer operator->() const;				(C++17 起) (C++20 中弃用)

返回到当前元素的右值引用或指针。

1) 等价于 static_cast<reference>(*base()) (C++20 前)ranges::iter_move(base()) (C++20 起) 。

2) 等价于 base() 。

参数

（无）

返回值

1) 到当前元素的右值引用或其副本。

2) 底层迭代器的副本。若直接使用 -> 则最终返回指向当前元素的指针。

注解

注意若直接使用 -> 则 (2) 最终返回指针。解引用指针时，返回值是左值。这可能导致非有意的行为。

示例

运行此代码

#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
void print(auto rem, auto const& v) {
    for (std::cout << rem; auto const& e : v)
        std::cout << 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('!'); // 调用 -> string::push_back(char)
        q.emplace_back( *it );
    }
    print("2) p: ", p);
    print("3) q: ", q);
 
    std::vector v{1,2,3};
    std::move_iterator it{v.begin()};
    // *it = 13; // 错误：将右值用作左值
}

输出：

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

缺陷报告

下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。

DR	应用于	出版时的行为	正确行为
LWG 2106	C++11	若解引用底层迭代器返回纯右值则解引用 move_iterator 能返回悬垂引用	替而返回对象

参阅

operator[] (C++11)

按索引访问元素 (公开成员函数)