std::reverse_iterator<Iter>::operator=

 

C++

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自立实现与有宿主实现

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功能特性测试宏 (C++20)

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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::reverse_iterator

成员函数

reverse_iterator::reverse_iterator

reverse_iterator::operator=

reverse_iterator::base

reverse_iterator::operator*reverse_iterator::operator->

reverse_iterator::operator[]

reverse_iterator::operator++reverse_iterator::operator+reverse_iterator::operator+=reverse_iterator::operator--reverse_iterator::operator-reverse_iterator::operator-=

非成员函数

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

operator+

operator-

iter_move (C++20)

iter_swap (C++20)

make_reverse_iterator (C++14)

 

<tbody> </tbody>

template< class U > reverse_iterator& operator=( const reverse_iterator<U>& other );		(C++17 起为 constexpr)

See More

将 other.current 赋给 current。

此重载只有在 std::is_same_v<U, Iter> 是 false 且 std::convertible_to<const U&, Iter> 和 std::assignable_from<Iter&, const U&> 均得到实现时才会参与重载决议。

(C++20 起)

参数

other

-

要赋值的迭代器适配器

返回值

*this

示例

运行此代码

#include <iostream>
#include <iterator>

int main()
{
    const int a1[]{0, 1, 2};
    int a2[]{0, 1, 2, 3};
    short a3[]{40, 41, 42};
    
    std::reverse_iterator<const int*> it1{std::crbegin(a1)};
    it1 = std::reverse_iterator<int*>{std::rbegin(a2)};   // OK
//  it1 = std::reverse_iterator<short*>{std::rbegin(a3)}; // 编译错误：指针类型不兼容
    
    std::reverse_iterator<const short*> it2{nullptr};
    it2 = std::rbegin(a3); // OK
//  it2 = std::begin(a3);  // 编译错误：没有可行的 operator= 重载
    std::cout << *it2 << '\n';
}

输出：

42

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。

缺陷报告	应用于	出版时的行为	正确行为
LWG 280	C++98	不允许异质赋值	允许异质赋值
LWG 3435	C++20	转换赋值运算符未受约束	已约束

参阅

(构造函数)

构造新的 reverse_iterator (公开成员函数)