operator-(std::reverse_iterator)

 

C++

编译器支持

自立实现与有宿主实现

语言

标准库

标准库标头

具名要求

功能特性测试宏 (C++20)

语言支持库

概念库 (C++20)

元编程库 (C++11)

诊断库

通用工具库

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)

并发支持库 (C++11)

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) 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) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) 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) make_const_iterator (C++23) make_const_sentinel (C++23) 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::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)

 

template< class Iterator1, class Iterator2 > typename reverse_iterator<Iterator1>::difference_type     operator-( const reverse_iterator<Iterator1>& lhs,                const reverse_iterator<Iterator2>& rhs );		(C++11 前)
template< class Iterator1, class Iterator2 > auto operator-( const reverse_iterator<Iterator1>& lhs,                 const reverse_iterator<Iterator2>& rhs               ) -> decltype(rhs.base() - lhs.base());		(C++11 起) (C++17 前)
template< class Iterator1, class Iterator2 > constexpr auto operator-( const reverse_iterator<Iterator1>& lhs,                           const reverse_iterator<Iterator2>& rhs                         ) -> decltype(rhs.base() - lhs.base());		(C++17 起)

返回两个迭代器适配器间的距离。

参数

lhs, rhs

-

要计算距离的迭代器适配器

返回值

rhs.base() - lhs.base()

示例

运行此代码

#include <iostream>
#include <iterator>
#include <list>
#include <vector>
 
int main()
{
    std::vector v{0, 1, 2, 3};
    std::reverse_iterator<std::vector<int>::iterator>
        vec_ri1{std::reverse_iterator{v.rbegin()}},
        vec_ri2{std::reverse_iterator{v.rend()}};
    std::cout << (ri2 - ri1) << ' '; // 4
    std::cout << (ri1 - ri2) << '\n'; // -4
 
    std::list l{5, 6, 7, 8};
    std::reverse_iterator<std::list<int>::iterator>
        lst_ri1{std::reverse_iterator{l.rbegin()}},
        lst_ri2{std::reverse_iterator{l.rend()}};
//  auto n = (ri1 - ri2); // 错误：底层迭代器没有实现随机访问迭代器
}

输出：

4 -4

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	底层迭代器类型不同的 std::reverse_iterator 无法相减	可以相减

参阅

operator++operator++(int)operator+=operator+operator--operator--(int)operator-=operator-	推进或回退迭代器 (公开成员函数)
operator+	令迭代器前进 (函数模板)